diff --git a/composer.json b/composer.json
index 39882e2..47f8ac3 100644
--- a/composer.json
+++ b/composer.json
@@ -18,8 +18,8 @@
         "psr/clock": "^1.0",
         "psr/log": "^2.0 | ^3.0",
         "simplesamlphp/assert": "^1.8",
-        "simplesamlphp/xml-common": "~1.24.0",
-        "simplesamlphp/xml-security": "~1.13.0"
+        "simplesamlphp/xml-common": "dev-feature/xsd-types",
+        "simplesamlphp/xml-security": "dev-feature/xsd-types"
     },
     "require-dev": {
         "beste/clock": "^3.0",
diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
deleted file mode 100644
index 3c94f85..0000000
--- a/phpstan-baseline.neon
+++ /dev/null
@@ -1,76 +0,0 @@
-parameters:
-	ignoreErrors:
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractCondition\\)\\:\\:XSI_TYPE_NAME\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractCondition.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractCondition\\)\\:\\:XSI_TYPE_NAMESPACE\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractCondition.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractCondition\\)\\:\\:XSI_TYPE_PREFIX\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractCondition.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractStatement\\)\\:\\:XSI_TYPE_NAME\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractStatement.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractStatement\\)\\:\\:XSI_TYPE_NAMESPACE\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractStatement.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractStatement\\)\\:\\:XSI_TYPE_PREFIX\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractStatement.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractSubjectStatement\\)\\:\\:XSI_TYPE_NAME\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractSubjectStatement.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractSubjectStatement\\)\\:\\:XSI_TYPE_NAMESPACE\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractSubjectStatement.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\saml\\\\AbstractSubjectStatement\\)\\:\\:XSI_TYPE_PREFIX\\.$#"
-			count: 2
-			path: src/SAML11/XML/saml/AbstractSubjectStatement.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\samlp\\\\AbstractQuery\\)\\:\\:XSI_TYPE_NAME\\.$#"
-			count: 2
-			path: src/SAML11/XML/samlp/AbstractQuery.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\samlp\\\\AbstractQuery\\)\\:\\:XSI_TYPE_NAMESPACE\\.$#"
-			count: 2
-			path: src/SAML11/XML/samlp/AbstractQuery.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\samlp\\\\AbstractQuery\\)\\:\\:XSI_TYPE_PREFIX\\.$#"
-			count: 2
-			path: src/SAML11/XML/samlp/AbstractQuery.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\samlp\\\\AbstractSubjectQuery\\)\\:\\:XSI_TYPE_NAME\\.$#"
-			count: 2
-			path: src/SAML11/XML/samlp/AbstractSubjectQuery.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\samlp\\\\AbstractSubjectQuery\\)\\:\\:XSI_TYPE_NAMESPACE\\.$#"
-			count: 2
-			path: src/SAML11/XML/samlp/AbstractSubjectQuery.php
-
-		-
-			message: "#^Access to undefined constant static\\(SimpleSAML\\\\SAML11\\\\XML\\\\samlp\\\\AbstractSubjectQuery\\)\\:\\:XSI_TYPE_PREFIX\\.$#"
-			count: 2
-			path: src/SAML11/XML/samlp/AbstractSubjectQuery.php
diff --git a/phpstan.neon b/phpstan.neon
index e4c4cf7..21cf590 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -2,5 +2,3 @@ parameters:
   level: 1
   paths:
     - src
-includes:
-  - phpstan-baseline.neon
diff --git a/src/SAML11/Assert/AnyURITrait.php b/src/SAML11/Assert/AnyURITrait.php
new file mode 100644
index 0000000..a85a848
--- /dev/null
+++ b/src/SAML11/Assert/AnyURITrait.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Assert;
+
+use SimpleSAML\Assert\AssertionFailedException;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+
+/**
+ * @package simplesamlphp/saml11
+ */
+trait AnyURITrait
+{
+    /**
+     * @param string $value
+     * @param string $message
+     */
+    protected static function validAnyURI(string $value, string $message = ''): void
+    {
+        parent::validAnyURI($value, $message);
+
+        try {
+            /**
+             * 1.2.1 String and URI Values
+             *
+             * Unless otherwise indicated in this specification, all URI reference values MUST consist
+             * of at least one non-whitespace character
+             */
+            static::notWhitespaceOnly(
+                $value,
+                $message ?: '%s is not a SAML1.1-compliant URI',
+                ProtocolViolationException::class,
+            );
+        } catch (AssertionFailedException $e) {
+            throw new ProtocolViolationException($e->getMessage());
+        }
+    }
+}
diff --git a/src/SAML11/Assert/Assert.php b/src/SAML11/Assert/Assert.php
index aa3a9e8..a3d7761 100644
--- a/src/SAML11/Assert/Assert.php
+++ b/src/SAML11/Assert/Assert.php
@@ -12,16 +12,18 @@
  * @package simplesamlphp/saml11
  *
  * @method static void validDateTime(mixed $value, string $message = '', string $exception = '')
- * @method static void validURI(mixed $value, string $message = '', string $exception = '')
  * @method static void validEntityID(mixed $value, string $message = '', string $exception = '')
+ * @method static void validURI(mixed $value, string $message = '', string $exception = '')
  * @method static void nullOrValidDateTime(mixed $value, string $message = '', string $exception = '')
- * @method static void nullOrValidURI(mixed $value, string $message = '', string $exception = '')
  * @method static void nullOrValidEntityID(mixed $value, string $message = '', string $exception = '')
+ * @method static void nullOrValidURI(mixed $value, string $message = '', string $exception = '')
  * @method static void allValidDateTime(mixed $value, string $message = '', string $exception = '')
- * @method static void allValidURI(mixed $value, string $message = '', string $exception = '')
  * @method static void allValidEntityID(mixed $value, string $message = '', string $exception = '')
+ * @method static void allValidURI(mixed $value, string $message = '', string $exception = '')
  */
 class Assert extends BaseAssert
 {
-    use CustomAssertionTrait;
+    use AnyURITrait;
+    use DateTimeTrait;
+    use StringTrait;
 }
diff --git a/src/SAML11/Assert/CustomAssertionTrait.php b/src/SAML11/Assert/CustomAssertionTrait.php
deleted file mode 100644
index 18e2571..0000000
--- a/src/SAML11/Assert/CustomAssertionTrait.php
+++ /dev/null
@@ -1,63 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace SimpleSAML\SAML11\Assert;
-
-use SimpleSAML\Assert\AssertionFailedException;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-
-/**
- * @package simplesamlphp/assert
- */
-trait CustomAssertionTrait
-{
-    private static string $scheme_regex = '/^([a-z][a-z0-9\+\-\.]+[:])/i';
-
-    /***********************************************************************************
-     *  NOTE:  Custom assertions may be added below this line.                         *
-     *         They SHOULD be marked as `protected` to ensure the call is forced       *
-     *          through __callStatic().                                                *
-     *         Assertions marked `public` are called directly and will                 *
-     *          not handle any custom exception passed to it.                          *
-     ***********************************************************************************/
-
-
-    /**
-     * @param string $value
-     * @param string $message
-     */
-    protected static function validDateTime(string $value, string $message = ''): void
-    {
-        parent::validDateTime($value, $message, SchemaViolationException::class);
-
-        try {
-            static::endsWith(
-                $value,
-                'Z',
-                $message ?: '%s is not a DateTime expressed in the UTC timezone using the \'Z\' timezone identifier.',
-            );
-        } catch (AssertionFailedException $e) {
-            throw new ProtocolViolationException($e->getMessage());
-        }
-    }
-
-
-    /**
-     * @param string $value
-     * @param string $message
-     */
-    protected static function validURI(string $value, string $message = ''): void
-    {
-        parent::validURI($value, $message, SchemaViolationException::class);
-
-        try {
-            static::notWhitespaceOnly($value, $message ?: '%s is not a SAML1.1-compliant URI');
-            // If it doesn't have a scheme, it's not an absolute URI
-            static::regex($value, self::$scheme_regex, $message ?: '%s is not a SAML1.1-compliant URI');
-        } catch (AssertionFailedException $e) {
-            throw new ProtocolViolationException($e->getMessage());
-        }
-    }
-}
diff --git a/src/SAML11/Assert/DateTimeTrait.php b/src/SAML11/Assert/DateTimeTrait.php
new file mode 100644
index 0000000..e25dd89
--- /dev/null
+++ b/src/SAML11/Assert/DateTimeTrait.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Assert;
+
+use SimpleSAML\Assert\AssertionFailedException;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+
+/**
+ * @package simplesamlphp/saml11
+ */
+trait DateTimeTrait
+{
+    /**
+     * @param string $value
+     * @param string $message
+     */
+    protected static function validDateTime(string $value, string $message = ''): void
+    {
+        parent::validDateTime($value, $message);
+
+        try {
+            /**
+             * 1.2.2 Time Values
+             *
+             * All SAML time values have the type xsd:dateTime, which is built in to the W3C XML Schema Datatypes
+             * specification [Schema2], and MUST be expressed in UTC form
+             */
+            static::endsWith(
+                $value,
+                'Z',
+                $message ?: '%s is not a DateTime expressed in the UTC timezone using the \'Z\' timezone identifier.',
+            );
+        } catch (AssertionFailedException $e) {
+            throw new ProtocolViolationException($e->getMessage());
+        }
+    }
+}
diff --git a/src/SAML11/Assert/StringTrait.php b/src/SAML11/Assert/StringTrait.php
new file mode 100644
index 0000000..52b8a0e
--- /dev/null
+++ b/src/SAML11/Assert/StringTrait.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Assert;
+
+use SimpleSAML\Assert\AssertionFailedException;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+
+/**
+ * @package simplesamlphp/saml11
+ */
+trait StringTrait
+{
+    /**
+     * @param string $value
+     * @param string $message
+     */
+    protected static function validString(string $value, string $message = ''): void
+    {
+        parent::validString($value, $message, SchemaViolationException::class);
+
+        try {
+            /**
+             * 1.2.1 String and URI Values
+             *
+             * All strings in SAML messages MUST consist of at least one non-whitespace character
+             * (whitespace is defined in the XML Recommendation [XML] §2.3).
+             * Empty and whitespace-only values are disallowed.
+             */
+            static::notWhitespaceOnly($value, $message ?: '%s is not a SAML1.1-compliant string');
+        } catch (AssertionFailedException $e) {
+            throw new ProtocolViolationException($e->getMessage());
+        }
+    }
+}
diff --git a/src/SAML11/Compat/AbstractContainer.php b/src/SAML11/Compat/AbstractContainer.php
index a5e25d6..5724d59 100644
--- a/src/SAML11/Compat/AbstractContainer.php
+++ b/src/SAML11/Compat/AbstractContainer.php
@@ -8,24 +8,23 @@
 use Psr\Log\LoggerInterface;
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\XML\ExtensionPointInterface;
-use SimpleSAML\XML\AbstractElement;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\{AbstractElement, ElementInterface};
+use SimpleSAML\XML\Type\QNameValue;
 use SimpleSAML\XMLSecurity\Alg\Encryption\EncryptionAlgorithmFactory;
 use SimpleSAML\XMLSecurity\Alg\KeyTransport\KeyTransportAlgorithmFactory;
 use SimpleSAML\XMLSecurity\Alg\Signature\SignatureAlgorithmFactory;
 
 use function array_key_exists;
-use function implode;
-use function is_subclass_of;
+use function strval;
 
 abstract class AbstractContainer
 {
-    /** @var string */
-    private const XSI_TYPE_PREFIX = '<xsi:type>';
-
     /** @var array */
     protected array $registry = [];
 
+    /** @var array */
+    protected array $extRegistry = [];
+
     /** @var array|null */
     protected ?array $blacklistedEncryptionAlgorithms = [
         EncryptionAlgorithmFactory::DEFAULT_BLACKLIST,
@@ -46,6 +45,20 @@ public function getBlacklistedEncryptionAlgorithms(): ?array
     }
 
 
+    /**
+     * Register a class that can handle a given element.
+     *
+     * @param string $class The class name of a class extending AbstractElement
+     * @psalm-param class-string $class
+     */
+    public function registerElementHandler(string $class): void
+    {
+        Assert::subclassOf($class, AbstractElement::class);
+        $key = '{' . strval($class::NS) . '}' . AbstractElement::getClassName($class);
+        $this->registry[$key] = $class;
+    }
+
+
     /**
      * Register a class that can handle given extension points of the standard.
      *
@@ -54,37 +67,29 @@ public function getBlacklistedEncryptionAlgorithms(): ?array
      */
     public function registerExtensionHandler(string $class): void
     {
-        Assert::subclassOf($class, AbstractElement::class);
-        if (is_subclass_of($class, ExtensionPointInterface::class, true)) {
-            $key = implode(':', [self::XSI_TYPE_PREFIX, $class::getXsiTypeNamespaceURI(), $class::getXsiTypeName()]);
-        } else {
-            $className = AbstractElement::getClassName($class);
-            $key = ($class::NS === null) ? $className : implode(':', [$class::NS, $className]);
-        }
-        $this->registry[$key] = $class;
+        Assert::subclassOf($class, ExtensionPointInterface::class);
+        $key = '{' . $class::getXsiTypeNamespaceURI() . '}' . $class::getXsiTypeName();
+        $this->extRegistry[$key] = $class;
     }
 
 
     /**
-     * Search for a class that implements an $element in the given $namespace.
+     * Search for a class that implements an element in the given $namespace.
      *
      * Such classes must have been registered previously by calling registerExtensionHandler(), and they must
      * extend \SimpleSAML\XML\AbstractElement.
      *
-     * @param string|null $namespace The namespace URI for the given element.
-     * @param string $element The local name of the element.
+     * @param \SimpleSAML\XML\Type\QNameValue|null $qName The qualified name of the element.
      *
      * @return string|null The fully-qualified name of a class extending \SimpleSAML\XML\AbstractElement and
      * implementing support for the given element, or null if no such class has been registered before.
      * @psalm-return class-string|null
      */
-    public function getElementHandler(?string $namespace, string $element): ?string
+    public function getElementHandler(QNameValue $qName): ?string
     {
-        Assert::nullOrValidURI($namespace, SchemaViolationException::class);
-        Assert::validNCName($element, SchemaViolationException::class);
-
-        $key = ($namespace === null) ? $element : implode(':', [$namespace, $element]);
+        $key = '{' . strval($qName->getNameSpaceURI()) . '}' . strval($qName->getLocalName());
         if (array_key_exists($key, $this->registry) === true) {
+            Assert::implementsInterface($this->registry[$key], ElementInterface::class);
             return $this->registry[$key];
         }
 
@@ -98,21 +103,20 @@ public function getElementHandler(?string $namespace, string $element): ?string
      * Such classes must have been registered previously by calling registerExtensionHandler(), and they must
      * implement \SimpleSAML\SAML11\XML\saml\ExtensionPointInterface.
      *
-     * @param string $type The type of the identifier (xsi:type of a BaseID element).
-     *
+     * @param \SimpleSAML\XML\Type\QNameValue $qName The qualified name of the extension.
      * @return string|null The fully-qualified name of a class implementing
      *  \SimpleSAML\SAML11\XML\saml\ExtensionPointInterface or null if no such class has been registered before.
      * @psalm-return class-string|null
      */
-    public function getExtensionHandler(string $type): ?string
+    public function getExtensionHandler(QNameValue $qName): ?string
     {
-        Assert::notEmpty($type, 'Cannot search for identifier handlers with an empty type.');
-        $type = implode(':', [self::XSI_TYPE_PREFIX, $type]);
-        if (!array_key_exists($type, $this->registry)) {
-            return null;
+        $key = '{' . strval($qName->getNameSpaceURI()) . '}' . strval($qName->getLocalName());
+        if (array_key_exists($key, $this->extRegistry) === true) {
+            Assert::implementsInterface($this->extRegistry[$key], ExtensionPointInterface::class);
+            return $this->extRegistry[$key];
         }
-        Assert::implementsInterface($this->registry[$type], ExtensionPointInterface::class);
-        return $this->registry[$type];
+
+        return null;
     }
 
 
diff --git a/src/SAML11/Constants.php b/src/SAML11/Constants.php
index 8660be4..2a14e5f 100644
--- a/src/SAML11/Constants.php
+++ b/src/SAML11/Constants.php
@@ -71,11 +71,6 @@ class Constants extends \SimpleSAML\XMLSecurity\Constants
      */
     public const CM_BEARER = 'urn:oasis:names:tc:SAML:1.0:cm:bearer';
 
-    /**
-     * The format to express a timestamp in SAML 1.1
-     */
-    public const DATETIME_FORMAT = 'Y-m-d\\TH:i:sp';
-
     /**
      * Email address NameID format.
      */
@@ -182,4 +177,18 @@ class Constants extends \SimpleSAML\XMLSecurity\Constants
      * Top-level status code.
      */
     public const STATUS_VERSION_MISMATCH = 'samlp:VersionMismatch';
+
+    /** @var string[] */
+    public static array $STATUS_CODES = [
+        self::STATUS_REQUEST_DENIED,
+        self::STATUS_REQUEST_VERSION_DEPRECATED,
+        self::STATUS_REQUEST_VERSION_TOO_HIGH,
+        self::STATUS_REQUEST_VERSION_TOO_LOW,
+        self::STATUS_REQUESTER,
+        self::STATUS_RESOURCE_NOT_RECOGNIZED,
+        self::STATUS_RESPONDER,
+        self::STATUS_SUCCESS,
+        self::STATUS_TOO_MANY_RESPONSES,
+        self::STATUS_VERSION_MISMATCH,
+    ];
 }
diff --git a/src/SAML11/Type/AnyURIValue.php b/src/SAML11/Type/AnyURIValue.php
new file mode 100644
index 0000000..87de10f
--- /dev/null
+++ b/src/SAML11/Type/AnyURIValue.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Type;
+
+use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\XML\Type\AnyURIValue as BaseAnyURIValue;
+
+/**
+ * @package simplesaml/saml11
+ */
+class AnyURIValue extends BaseAnyURIValue
+{
+    /**
+     * Validate the value.
+     *
+     * @param string $value
+     * @return void
+     */
+    protected function validateValue(string $value): void
+    {
+        // Note: value must already be sanitized before validating
+        Assert::validAnyURI($this->sanitizeValue($value));
+    }
+}
diff --git a/src/SAML11/Type/DateTimeValue.php b/src/SAML11/Type/DateTimeValue.php
new file mode 100644
index 0000000..7aecaca
--- /dev/null
+++ b/src/SAML11/Type/DateTimeValue.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Type;
+
+use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\XML\Type\DateTimeValue as BaseDateTimeValue;
+
+/**
+ * @package simplesaml/saml11
+ */
+class DateTimeValue extends BaseDateTimeValue
+{
+    // Lowercase p as opposed to the base-class to covert the timestamp to UTC as demanded by the SAML specifications
+    public const DATETIME_FORMAT = 'Y-m-d\\TH:i:sp';
+
+
+    /**
+     * Validate the value.
+     *
+     * @param string $value
+     * @return void
+     */
+    protected function validateValue(string $value): void
+    {
+        // Note: value must already be sanitized before validating
+        Assert::validDateTime($this->sanitizeValue($value));
+    }
+}
diff --git a/src/SAML11/Type/StringValue.php b/src/SAML11/Type/StringValue.php
new file mode 100644
index 0000000..514f621
--- /dev/null
+++ b/src/SAML11/Type/StringValue.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Type;
+
+use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\XML\Type\StringValue as BaseStringValue;
+
+/**
+ * @package simplesaml/saml11
+ */
+class StringValue extends BaseStringValue
+{
+    /**
+     * Validate the value.
+     *
+     * @param string $value
+     * @return void
+     */
+    protected function validateValue(string $value): void
+    {
+        // Note: value must already be sanitized before validating
+        Assert::validString($this->sanitizeValue($value));
+    }
+}
diff --git a/src/SAML11/XML/ExtensionPointInterface.php b/src/SAML11/XML/ExtensionPointInterface.php
index 74bec7a..57f8056 100644
--- a/src/SAML11/XML/ExtensionPointInterface.php
+++ b/src/SAML11/XML/ExtensionPointInterface.php
@@ -4,6 +4,8 @@
 
 namespace SimpleSAML\SAML11\XML;
 
+use SimpleSAML\XML\Type\{AnyURIValue, NCNameValue, QNameValue};
+
 /**
  * Interface for several extension points objects.
  *
@@ -14,31 +16,31 @@ interface ExtensionPointInterface
     /**
      * Get the local name for the element's xsi:type.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\NCNameValue
      */
-    public static function getXsiTypeName(): string;
+    public static function getXsiTypeName(): NCNameValue;
 
 
     /**
      * Get the namespace for the element's xsi:type.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\AnyURIValue
      */
-    public static function getXsiTypeNamespaceURI(): string;
+    public static function getXsiTypeNamespaceURI(): AnyURIValue;
 
 
     /**
      * Get the namespace-prefix for the element's xsi:type.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\NCNameValue
      */
-    public static function getXsiTypePrefix(): string;
+    public static function getXsiTypePrefix(): NCNameValue;
 
 
     /**
      * Return the xsi:type value corresponding this element.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getXsiType(): string;
+    public function getXsiType(): QNameValue;
 }
diff --git a/src/SAML11/XML/ExtensionPointTrait.php b/src/SAML11/XML/ExtensionPointTrait.php
index 30530e1..8247d29 100644
--- a/src/SAML11/XML/ExtensionPointTrait.php
+++ b/src/SAML11/XML/ExtensionPointTrait.php
@@ -6,7 +6,11 @@
 
 use RuntimeException;
 use SimpleSAML\SAML11\Assert\Assert;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Type\{AnyURIValue, NCNameValue, QNameValue};
+
+use function constant;
+use function defined;
+use function sprintf;
 
 /**
  * Trait for several extension points objects.
@@ -16,9 +20,9 @@
 trait ExtensionPointTrait
 {
     /**
-     * @inheritDoc
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getXsiType(): string
+    public function getXsiType(): QNameValue
     {
         return $this->type;
     }
@@ -27,9 +31,9 @@ public function getXsiType(): string
     /**
      * Get the local name for the element's xsi:type.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\NCNameValue
      */
-    public static function getXsiTypeName(): string
+    public static function getXsiTypeName(): NCNameValue
     {
         Assert::true(
             defined('static::XSI_TYPE_NAME'),
@@ -38,17 +42,16 @@ public static function getXsiTypeName(): string
             RuntimeException::class,
         );
 
-        Assert::validNCName(static::XSI_TYPE_NAME, SchemaViolationException::class);
-        return static::XSI_TYPE_NAME;
+        return NCNameValue::fromString(constant('static::XSI_TYPE_NAME'));
     }
 
 
     /**
      * Get the namespace for the element's xsi:type.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\AnyURIValue
      */
-    public static function getXsiTypeNamespaceURI(): string
+    public static function getXsiTypeNamespaceURI(): AnyURIValue
     {
         Assert::true(
             defined('static::XSI_TYPE_NAMESPACE'),
@@ -57,17 +60,16 @@ public static function getXsiTypeNamespaceURI(): string
             RuntimeException::class,
         );
 
-        Assert::validURI(static::XSI_TYPE_NAMESPACE, SchemaViolationException::class);
-        return static::XSI_TYPE_NAMESPACE;
+        return AnyURIValue::fromString(constant('static::XSI_TYPE_NAMESPACE'));
     }
 
 
     /**
      * Get the namespace-prefix for the element's xsi:type.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\NCNameValue
      */
-    public static function getXsiTypePrefix(): string
+    public static function getXsiTypePrefix(): NCNameValue
     {
         Assert::true(
             defined('static::XSI_TYPE_PREFIX'),
@@ -78,7 +80,6 @@ public static function getXsiTypePrefix(): string
             RuntimeException::class,
         );
 
-        Assert::validNCName(static::XSI_TYPE_PREFIX, SchemaViolationException::class);
-        return static::XSI_TYPE_PREFIX;
+        return NCNameValue::fromString(constant('static::XSI_TYPE_PREFIX'));
     }
 }
diff --git a/src/SAML11/XML/SignableElementTrait.php b/src/SAML11/XML/SignableElementTrait.php
index 806ce9e..1a2db79 100644
--- a/src/SAML11/XML/SignableElementTrait.php
+++ b/src/SAML11/XML/SignableElementTrait.php
@@ -8,19 +8,21 @@
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Compat\ContainerSingleton;
 use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\Type\{AnyURIValue, Base64BinaryValue};
 use SimpleSAML\XMLSecurity\Alg\Signature\SignatureAlgorithmInterface;
 use SimpleSAML\XMLSecurity\Constants as C;
-use SimpleSAML\XMLSecurity\Exception\RuntimeException;
-use SimpleSAML\XMLSecurity\Exception\UnsupportedAlgorithmException;
+use SimpleSAML\XMLSecurity\Exception\{RuntimeException, UnsupportedAlgorithmException};
 use SimpleSAML\XMLSecurity\Utils\XML;
-use SimpleSAML\XMLSecurity\XML\ds\CanonicalizationMethod;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\Signature;
-use SimpleSAML\XMLSecurity\XML\ds\SignatureMethod;
-use SimpleSAML\XMLSecurity\XML\ds\SignatureValue;
-use SimpleSAML\XMLSecurity\XML\ds\SignedInfo;
-use SimpleSAML\XMLSecurity\XML\ds\Transform;
-use SimpleSAML\XMLSecurity\XML\ds\Transforms;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    CanonicalizationMethod,
+    KeyInfo,
+    Signature,
+    SignatureMethod,
+    SignatureValue,
+    SignedInfo,
+    Transform,
+    Transforms,
+};
 use SimpleSAML\XMLSecurity\XML\SignableElementTrait as BaseSignableElementTrait;
 
 use function base64_encode;
@@ -60,12 +62,7 @@ public function sign(
         $this->keyInfo = $keyInfo;
         Assert::oneOf(
             $canonicalizationAlg,
-            [
-                C::C14N_INCLUSIVE_WITH_COMMENTS,
-                C::C14N_INCLUSIVE_WITHOUT_COMMENTS,
-                C::C14N_EXCLUSIVE_WITH_COMMENTS,
-                C::C14N_EXCLUSIVE_WITHOUT_COMMENTS,
-            ],
+            C::$CANONICALIZATION_ALGORITHMS,
             'Unsupported canonicalization algorithm: %s',
             UnsupportedAlgorithmException::class,
         );
@@ -105,26 +102,44 @@ protected function doSign(DOMElement $xml): DOMElement
              * 5.4.1: SAML assertions and protocols MUST use enveloped signatures when
              * signing assertions and protocol messages
              */
-            new Transform(C::XMLDSIG_ENVELOPED),
-            new Transform($this->c14nAlg),
+            new Transform(
+                AnyURIValue::fromString(C::XMLDSIG_ENVELOPED),
+            ),
+            new Transform(
+                AnyURIValue::fromString($this->c14nAlg),
+            ),
         ]);
 
         $canonicalDocument = XML::processTransforms($transforms, $xml);
 
         $signedInfo = new SignedInfo(
-            new CanonicalizationMethod($this->c14nAlg),
-            new SignatureMethod($algorithm),
+            new CanonicalizationMethod(
+                AnyURIValue::fromString($this->c14nAlg),
+            ),
+            new SignatureMethod(
+                AnyURIValue::fromString($algorithm),
+            ),
             [$this->getReference($digest, $transforms, $xml, $canonicalDocument)],
         );
 
         $signingData = $signedInfo->canonicalize($this->c14nAlg);
         $signedData = base64_encode($this->signer->sign($signingData));
 
-        $this->signature = new Signature($signedInfo, new SignatureValue($signedData), $this->keyInfo);
+        $this->signature = new Signature(
+            $signedInfo,
+            new SignatureValue(
+                Base64BinaryValue::fromString($signedData),
+            ),
+            $this->keyInfo,
+        );
+
         return DOMDocumentFactory::fromString($canonicalDocument)->documentElement;
     }
 
 
+    /**
+     * @return array|null
+     */
     public function getBlacklistedAlgorithms(): ?array
     {
         $container = ContainerSingleton::getInstance();
diff --git a/src/SAML11/XML/SignedElementTrait.php b/src/SAML11/XML/SignedElementTrait.php
index 7f1825c..7dc53d0 100644
--- a/src/SAML11/XML/SignedElementTrait.php
+++ b/src/SAML11/XML/SignedElementTrait.php
@@ -38,9 +38,8 @@ protected function setSignature(Signature $signature): void
 
         $reference = array_pop($references);
         Assert::notNull($reference->getURI(), "URI attribute not found.", ReferenceValidationFailedException::class);
-        Assert::validURI($reference->getURI(), ReferenceValidationFailedException::class);
         Assert::startsWith(
-            $reference->getURI(),
+            $reference->getURI()->getValue(),
             '#',
             "Reference must contain a same-document reference to the ID-attribute of the root element.",
             ReferenceValidationFailedException::class,
diff --git a/src/SAML11/XML/StringElementTrait.php b/src/SAML11/XML/StringElementTrait.php
deleted file mode 100644
index 11dcf60..0000000
--- a/src/SAML11/XML/StringElementTrait.php
+++ /dev/null
@@ -1,39 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace SimpleSAML\SAML11\XML;
-
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\XML\StringElementTrait as BaseStringElementTrait;
-
-/**
- * Trait extending the default StringElementTrait to comply with the restrictions added by the SAML 1.1 specifications.
- *
- * @package simplesamlphp/saml11
- */
-trait StringElementTrait
-{
-    use BaseStringElementTrait;
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(/** @scrutinizer ignore-unused */ string $content): void
-    {
-        /**
-         * 1.2.1 String and URI Values
-         *
-         * All SAML string and URI reference values have the types xsd:string and xsd:anyURI respectively, which
-         * are built in to the W3C XML Schema Datatypes specification [Schema2]. All strings in SAML messages
-         * MUST consist of at least one non-whitespace character (whitespace is defined in the XML
-         * Recommendation [XML] §2.3). Empty and whitespace-only values are disallowed.
-         */
-        Assert::notWhitespaceOnly($content, ProtocolViolationException::class);
-    }
-}
diff --git a/src/SAML11/XML/URIElementTrait.php b/src/SAML11/XML/URIElementTrait.php
deleted file mode 100644
index 6394ca2..0000000
--- a/src/SAML11/XML/URIElementTrait.php
+++ /dev/null
@@ -1,43 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace SimpleSAML\SAML11\XML;
-
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\URIElementTrait as BaseURIElementTrait;
-
-/**
- * Trait extending the default URIElementTrait to comply with the restrictions added by the SAML 1.1 specifications.
- *
- * @package simplesamlphp/saml11
- */
-trait URIElementTrait
-{
-    use BaseURIElementTrait;
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        /**
-         * 1.2.1 String and URI Values
-         *
-         * All SAML string and URI reference values have the types xsd:string and xsd:anyURI respectively, which
-         * are built in to the W3C XML Schema Datatypes specification [Schema2]. All strings in SAML messages
-         * MUST consist of at least one non-whitespace character (whitespace is defined in the XML
-         * Recommendation [XML] §2.3). Empty and whitespace-only values are disallowed. Also, unless otherwise
-         * indicated in this specification, all URI reference values MUST consist of at least one non-whitespace
-         * character, and are strongly RECOMMENDED to be absolute [RFC 2396].
-         */
-        Assert::notWhitespaceOnly($content, ProtocolViolationException::class);
-        Assert::validURI($content, SchemaViolationException::class);
-    }
-}
diff --git a/src/SAML11/XML/saml/AbstractActionType.php b/src/SAML11/XML/saml/AbstractActionType.php
index 0bb38ce..74ac0f0 100644
--- a/src/SAML11/XML/saml/AbstractActionType.php
+++ b/src/SAML11/XML/saml/AbstractActionType.php
@@ -6,9 +6,10 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\StringElementTrait;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
+
+use function strval;
 
 /**
  * SAML ActionType abstract data type.
@@ -17,30 +18,36 @@
  */
 abstract class AbstractActionType extends AbstractSamlElement
 {
-    use StringElementTrait;
-
-
     /**
      * Initialize a saml:AbstractActionType from scratch
      *
-     * @param string $value
-     * @param string|null $Namespace
+     * @param \SimpleSAML\SAML11\Type\StringValue $value
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue|null $Namespace
      */
     final public function __construct(
-        protected string $value,
-        protected ?string $Namespace = null,
+        protected StringValue $value,
+        protected ?AnyURIValue $Namespace = null,
     ) {
-        Assert::nullOrValidURI($Namespace, SchemaViolationException::class); // Covers the empty string
-        $this->setContent($value);
+    }
+
+
+    /**
+     * Collect the value of the element
+     *
+     * @return \SimpleSAML\SAML11\Type\StringValue|null
+     */
+    public function getValue(): StringValue
+    {
+        return $this->value;
     }
 
 
     /**
      * Collect the value of the Namespace-property
      *
-     * @return string|null
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue|null
      */
-    public function getNamespace(): ?string
+    public function getNamespace(): ?AnyURIValue
     {
         return $this->Namespace;
     }
@@ -60,9 +67,10 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $Namespace = self::getOptionalAttribute($xml, 'Namespace');
-
-        return new static($xml->textContent, $Namespace);
+        return new static(
+            StringValue::fromString($xml->textContent),
+            self::getOptionalAttribute($xml, 'Namespace', AnyURIValue::class),
+        );
     }
 
 
@@ -75,10 +83,10 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
-        $e->textContent = $this->getContent();
+        $e->textContent = strval($this->getValue());
 
         if ($this->getNamespace() !== null) {
-            $e->setAttribute('Namespace', $this->getNamespace());
+            $e->setAttribute('Namespace', strval($this->getNamespace()));
         }
 
         return $e;
diff --git a/src/SAML11/XML/saml/AbstractAdviceType.php b/src/SAML11/XML/saml/AbstractAdviceType.php
index c6ddb0f..1c6c6d3 100644
--- a/src/SAML11/XML/saml/AbstractAdviceType.php
+++ b/src/SAML11/XML/saml/AbstractAdviceType.php
@@ -8,8 +8,7 @@
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
 use SimpleSAML\XML\ExtendableElementTrait;
 use SimpleSAML\XML\XsNamespace as NS;
 
diff --git a/src/SAML11/XML/saml/AbstractAssertionType.php b/src/SAML11/XML/saml/AbstractAssertionType.php
index 56db8de..47947ff 100644
--- a/src/SAML11/XML/saml/AbstractAssertionType.php
+++ b/src/SAML11/XML/saml/AbstractAssertionType.php
@@ -4,28 +4,29 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Compat\ContainerSingleton;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Exception\VersionMismatchException;
 use SimpleSAML\SAML11\Utils\XPath;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\SAML11\Type\{DateTimeValue, StringValue};
+use SimpleSAML\XML\Exception\{
+    InvalidDOMElementException,
+    MissingElementException,
+    SchemaViolationException,
+    TooManyElementsException,
+};
+use SimpleSAML\XML\Type\{IDValue, NonNegativeIntegerValue};
 use SimpleSAML\XMLSecurity\XML\ds\Signature;
-use SimpleSAML\XMLSecurity\XML\SignableElementInterface;
-use SimpleSAML\XMLSecurity\XML\SignableElementTrait;
-use SimpleSAML\XMLSecurity\XML\SignedElementInterface;
-use SimpleSAML\XMLSecurity\XML\SignedElementTrait;
+use SimpleSAML\XMLSecurity\XML\{SignableElementInterface, SignableElementTrait};
+use SimpleSAML\XMLSecurity\XML\{SignedElementInterface, SignedElementTrait};
 
 use function array_filter;
 use function array_merge;
 use function array_pop;
 use function array_values;
-use function preg_replace;
+use function strval;
 
 /**
  * SAML Assertion Type abstract data type.
@@ -51,37 +52,63 @@ abstract class AbstractAssertionType extends AbstractSamlElement implements
     /**
      * Initialize a saml:AssertionType from scratch
      *
-     * @param string $assertionID
-     * @param string $issuer
-     * @param \DateTimeImmutable $issueInstant
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $majorVersion
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $minorVersion
+     * @param \SimpleSAML\XML\Type\IDValue $assertionID
+     * @param \SimpleSAML\SAML11\Type\StringValue $issuer
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue $issueInstant
      * @param \SimpleSAML\SAML11\XML\saml\Conditions|null $conditions
      * @param \SimpleSAML\SAML11\XML\saml\Advice|null $advice
      * @param array<\SimpleSAML\SAML11\XML\saml\AbstractStatementType> $statements
      */
     final public function __construct(
-        protected string $assertionID,
-        protected string $issuer,
-        protected DateTimeImmutable $issueInstant,
+        protected NonNegativeIntegerValue $majorVersion,
+        protected NonNegativeIntegerValue $minorVersion,
+        protected IDValue $assertionID,
+        protected StringValue $issuer,
+        protected DateTimeValue $issueInstant,
         protected ?Conditions $conditions = null,
         protected ?Advice $advice = null,
         protected array $statements = [],
     ) {
-        Assert::same($issueInstant->getTimeZone()->getName(), 'Z', ProtocolViolationException::class);
-        Assert::validNCName($assertionID, SchemaViolationException::class);
+        Assert::same($majorVersion->getValue(), '1', VersionMismatchException::class);
+        Assert::same($minorVersion->getValue(), '1', VersionMismatchException::class);
         Assert::minCount($statements, 1, MissingElementException::class);
         Assert::maxCount($statements, C::UNBOUNDED_LIMIT);
         Assert::allIsInstanceOf($statements, AbstractStatementType::class, SchemaViolationException::class);
     }
 
 
+    /**
+     * Collect the value of the majorVersion-property
+     *
+     * @return \SimpleSAML\XML\Type\NonNegativeIntegerValue
+     */
+    public function getMajorVersion(): NonNegativeIntegerValue
+    {
+        return $this->majorVersion;
+    }
+
+
+    /**
+     * Collect the value of the minorVersion-property
+     *
+     * @return \SimpleSAML\XML\Type\NonNegativeIntegerValue
+     */
+    public function getMinorVersion(): NonNegativeIntegerValue
+    {
+        return $this->minorVersion;
+    }
+
+
     /**
      * Collect the value of the assertionID-property
      *
      * Note: the name of this method is not consistent, but it has to be named getId for xml-security to work.
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\IDValue
      */
-    public function getId(): string
+    public function getId(): IDValue
     {
         return $this->assertionID;
     }
@@ -90,9 +117,9 @@ public function getId(): string
     /**
      * Collect the value of the issuer-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\StringValue
      */
-    public function getIssuer(): string
+    public function getIssuer(): StringValue
     {
         return $this->issuer;
     }
@@ -101,9 +128,9 @@ public function getIssuer(): string
     /**
      * Collect the value of the issueInstant-property
      *
-     * @return \DateTimeImmutable
+     * @return \SimpleSAML\SAML11\Type\DateTimeValue
      */
-    public function getIssueInstant(): DateTimeImmutable
+    public function getIssueInstant(): DateTimeValue
     {
         return $this->issueInstant;
     }
@@ -238,19 +265,6 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        Assert::same(self::getIntegerAttribute($xml, 'MajorVersion'), 1, 'Unsupported major version: %s');
-        Assert::same(self::getIntegerAttribute($xml, 'MinorVersion'), 1, 'Unsupported minor version: %s');
-
-        $assertionID = self::getAttribute($xml, 'AssertionID');
-        Assert::validNCName($assertionID); // Covers the empty string
-
-        $issueInstant = self::getAttribute($xml, 'IssueInstant');
-        // Strip sub-seconds - See paragraph 1.2.2 of SAML core specifications
-        $issueInstant = preg_replace('/([.][0-9]+Z)$/', 'Z', $issueInstant, 1);
-
-        Assert::validDateTime($issueInstant, ProtocolViolationException::class);
-        $issueInstant = new DateTimeImmutable($issueInstant);
-
         $conditions = Conditions::getChildrenOfClass($xml);
         Assert::maxCount(
             $conditions,
@@ -277,9 +291,11 @@ public static function fromXML(DOMElement $xml): static
         Assert::maxCount($signature, 1, 'Only one <ds:Signature> element is allowed.', TooManyElementsException::class);
 
         $assertion = new static(
-            $assertionID,
-            self::getAttribute($xml, 'Issuer'),
-            $issueInstant,
+            self::getAttribute($xml, 'MajorVersion', NonNegativeIntegerValue::class),
+            self::getAttribute($xml, 'MinorVersion', NonNegativeIntegerValue::class),
+            self::getAttribute($xml, 'AssertionID', IDValue::class),
+            self::getAttribute($xml, 'Issuer', StringValue::class),
+            self::getAttribute($xml, 'IssueInstant', DateTimeValue::class),
             array_pop($conditions),
             array_pop($advice),
             array_merge($statements, $subjectStatement, $authnStatement, $authzDecisionStatement, $attrStatement),
@@ -304,11 +320,11 @@ protected function toUnsignedXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
 
-        $e->setAttribute('MajorVersion', '1');
-        $e->setAttribute('MinorVersion', '1');
-        $e->setAttribute('AssertionID', $this->getId());
-        $e->setAttribute('Issuer', $this->getIssuer());
-        $e->setAttribute('IssueInstant', $this->getIssueInstant()->format(C::DATETIME_FORMAT));
+        $e->setAttribute('MajorVersion', strval($this->getMajorVersion()));
+        $e->setAttribute('MinorVersion', strval($this->getMinorVersion()));
+        $e->setAttribute('AssertionID', strval($this->getId()));
+        $e->setAttribute('Issuer', strval($this->getIssuer()));
+        $e->setAttribute('IssueInstant', strval($this->getIssueInstant()));
 
         $this->getConditions()?->toXML($e);
         $this->getAdvice()?->toXML($e);
diff --git a/src/SAML11/XML/saml/AbstractAttributeDesignatorType.php b/src/SAML11/XML/saml/AbstractAttributeDesignatorType.php
index dd3b5db..3886166 100644
--- a/src/SAML11/XML/saml/AbstractAttributeDesignatorType.php
+++ b/src/SAML11/XML/saml/AbstractAttributeDesignatorType.php
@@ -5,8 +5,9 @@
 namespace SimpleSAML\SAML11\XML\saml;
 
 use DOMElement;
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
+
+use function strval;
 
 /**
  * SAML AttributeDesignatorType abstract data type.
@@ -18,24 +19,22 @@ abstract class AbstractAttributeDesignatorType extends AbstractSamlElement
     /**
      * Initialize a saml:AttributeDesignatorType from scratch
      *
-     * @param string $AttributeName
-     * @param string $AttributeNamespace
+     * @param \SimpleSAML\SAML11\Type\StringValue $AttributeName
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $AttributeNamespace
      */
     public function __construct(
-        protected string $AttributeName,
-        protected string $AttributeNamespace,
+        protected StringValue $AttributeName,
+        protected AnyURIValue $AttributeNamespace,
     ) {
-        Assert::nullOrNotWhitespaceOnly($AttributeName, SchemaViolationException::class);
-        Assert::nullOrValidURI($AttributeNamespace, SchemaViolationException::class); // Covers the empty string
     }
 
 
     /**
      * Collect the value of the AttributeName-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\StringValue
      */
-    public function getAttributeName(): string
+    public function getAttributeName(): StringValue
     {
         return $this->AttributeName;
     }
@@ -44,9 +43,9 @@ public function getAttributeName(): string
     /**
      * Collect the value of the AttributeNamespace-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getAttributeNamespace(): string
+    public function getAttributeNamespace(): AnyURIValue
     {
         return $this->AttributeNamespace;
     }
@@ -62,8 +61,8 @@ public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
 
-        $e->setAttribute('AttributeName', $this->getAttributeName());
-        $e->setAttribute('AttributeNamespace', $this->getAttributeNamespace());
+        $e->setAttribute('AttributeName', strval($this->getAttributeName()));
+        $e->setAttribute('AttributeNamespace', strval($this->getAttributeNamespace()));
 
         return $e;
     }
diff --git a/src/SAML11/XML/saml/AbstractAttributeStatementType.php b/src/SAML11/XML/saml/AbstractAttributeStatementType.php
index 944e41c..5dcb9e8 100644
--- a/src/SAML11/XML/saml/AbstractAttributeStatementType.php
+++ b/src/SAML11/XML/saml/AbstractAttributeStatementType.php
@@ -7,9 +7,7 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\XML\Exception\{MissingElementException, SchemaViolationException, TooManyElementsException};
 
 /**
  * SAML AttributeStatementType abstract data type.
diff --git a/src/SAML11/XML/saml/AbstractAttributeType.php b/src/SAML11/XML/saml/AbstractAttributeType.php
index a210770..8d97e08 100644
--- a/src/SAML11/XML/saml/AbstractAttributeType.php
+++ b/src/SAML11/XML/saml/AbstractAttributeType.php
@@ -6,8 +6,8 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
 
 /**
  * SAML AttributeType abstract data type.
@@ -19,13 +19,13 @@ abstract class AbstractAttributeType extends AbstractAttributeDesignatorType
     /**
      * Initialize a saml:AttributeType from scratch
      *
-     * @param string $AttributeName
-     * @param string $AttributeNamespace
+     * @param \SimpleSAML\SAML11\Type\StringValue $AttributeName
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $AttributeNamespace
      * @param array<\SimpleSAML\SAML11\XML\saml\AttributeValue> $attributeValue
      */
     final public function __construct(
-        string $AttributeName,
-        string $AttributeNamespace,
+        StringValue $AttributeName,
+        AnyURIValue $AttributeNamespace,
         protected array $attributeValue,
     ) {
         Assert::allIsInstanceOf($attributeValue, AttributeValue::class, SchemaViolationException::class);
@@ -60,8 +60,8 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
         $attributeValue = AttributeValue::getChildrenOfClass($xml);
-        $AttributeName = self::getAttribute($xml, 'AttributeName');
-        $AttributeNamespace = self::getAttribute($xml, 'AttributeNamespace');
+        $AttributeName = self::getAttribute($xml, 'AttributeName', StringValue::class);
+        $AttributeNamespace = self::getAttribute($xml, 'AttributeNamespace', AnyURIValue::class);
 
         return new static($AttributeName, $AttributeNamespace, $attributeValue);
     }
diff --git a/src/SAML11/XML/saml/AbstractAudienceRestrictionConditionType.php b/src/SAML11/XML/saml/AbstractAudienceRestrictionConditionType.php
index 09cfe24..035181b 100644
--- a/src/SAML11/XML/saml/AbstractAudienceRestrictionConditionType.php
+++ b/src/SAML11/XML/saml/AbstractAudienceRestrictionConditionType.php
@@ -6,11 +6,7 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\saml\AbstractConditionType;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, SchemaViolationException};
 
 /**
  * @package simplesamlphp\saml11
diff --git a/src/SAML11/XML/saml/AbstractAuthenticationStatementType.php b/src/SAML11/XML/saml/AbstractAuthenticationStatementType.php
index 35d95a0..32b290a 100644
--- a/src/SAML11/XML/saml/AbstractAuthenticationStatementType.php
+++ b/src/SAML11/XML/saml/AbstractAuthenticationStatementType.php
@@ -4,16 +4,15 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Assert\Assert as SAMLAssert;
-use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\SAML11\Type\{AnyURIValue, DateTimeValue};
+use SimpleSAML\XML\Exception\{
+    InvalidDOMElementException,
+    MissingElementException,
+    SchemaViolationException,
+    TooManyElementsException,
+};
 
 /**
  * SAML AuthenticationStatementType abstract data type.
@@ -26,19 +25,18 @@ abstract class AbstractAuthenticationStatementType extends AbstractSubjectStatem
      * Initialize a saml:AuthenticationStatementType from scratch
      *
      * @param \SimpleSAML\SAML11\XML\saml\Subject $subject
-     * @param string $authenticationMethod
-     * @param \DateTimeImmutable $authenticationInstant
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $authenticationMethod
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue $authenticationInstant
      * @param \SimpleSAML\SAML11\XML\saml\SubjectLocality|null $subjectLocality
      * @param array<\SimpleSAML\SAML11\XML\saml\AuthorityBinding> $authorityBinding
      */
     final public function __construct(
         Subject $subject,
-        protected string $authenticationMethod,
-        protected DateTimeImmutable $authenticationInstant,
+        protected AnyURIValue $authenticationMethod,
+        protected DateTimeValue $authenticationInstant,
         protected ?SubjectLocality $subjectLocality = null,
         protected array $authorityBinding = [],
     ) {
-        SAMLAssert::validURI($authenticationMethod);
         Assert::allIsInstanceOf($authorityBinding, AuthorityBinding::class, SchemaViolationException::class);
 
         parent::__construct($subject);
@@ -70,9 +68,9 @@ public function getSubjectLocality(): ?SubjectLocality
     /**
      * Collect the value of the authenticationMethod-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getAuthenticationMethod(): string
+    public function getAuthenticationMethod(): AnyURIValue
     {
         return $this->authenticationMethod;
     }
@@ -81,9 +79,9 @@ public function getAuthenticationMethod(): string
     /**
      * Collect the value of the authenticationInstant-property
      *
-     * @return \DateTimeImmutable
+     * @return \SimpleSAML\SAML11\Type\DateTimeValue
      */
-    public function getAuthenticationInstant(): DateTimeImmutable
+    public function getAuthenticationInstant(): DateTimeValue
     {
         return $this->authenticationInstant;
     }
@@ -103,13 +101,6 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $authenticationInstant = self::getAttribute($xml, 'AuthenticationInstant');
-        // Strip sub-seconds - See paragraph 1.2.2 of SAML core specifications
-        $authenticationInstant = preg_replace('/([.][0-9]+Z)$/', 'Z', $authenticationInstant, 1);
-
-        SAMLAssert::validDateTime($authenticationInstant, ProtocolViolationException::class);
-        $authenticationInstant = new DateTimeImmutable($authenticationInstant);
-
         $authorityBinding = AuthorityBinding::getChildrenOfClass($xml);
         $subjectLocality = SubjectLocality::getChildrenOfClass($xml);
         Assert::maxCount($subjectLocality, 1, TooManyElementsException::class);
@@ -120,8 +111,8 @@ public static function fromXML(DOMElement $xml): static
 
         return new static(
             array_pop($subject),
-            self::getAttribute($xml, 'AuthenticationMethod'),
-            $authenticationInstant,
+            self::getAttribute($xml, 'AuthenticationMethod', AnyURIValue::class),
+            self::getAttribute($xml, 'AuthenticationInstant', DateTimeValue::class),
             array_pop($subjectLocality),
             $authorityBinding,
         );
@@ -138,8 +129,8 @@ public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toXML($parent);
 
-        $e->setAttribute('AuthenticationMethod', $this->getAuthenticationMethod());
-        $e->setAttribute('AuthenticationInstant', $this->getAuthenticationInstant()->format(C::DATETIME_FORMAT));
+        $e->setAttribute('AuthenticationMethod', strval($this->getAuthenticationMethod()));
+        $e->setAttribute('AuthenticationInstant', strval($this->getAuthenticationInstant()));
 
         $this->getSubjectLocality()?->toXML($e);
 
diff --git a/src/SAML11/XML/saml/AbstractAuthorityBindingType.php b/src/SAML11/XML/saml/AbstractAuthorityBindingType.php
index 052dd16..6a78d81 100644
--- a/src/SAML11/XML/saml/AbstractAuthorityBindingType.php
+++ b/src/SAML11/XML/saml/AbstractAuthorityBindingType.php
@@ -6,8 +6,11 @@
 
 use DOMElement;
 use SimpleSAML\SAML11\Assert\Assert;
-use SimpleSAML\SAML11\Constants as C;
+use SimpleSAML\SAML11\Type\AnyURIValue;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\XML\Type\QNameValue;
+
+use function strval;
 
 /**
  * SAML AuthorityBindingType abstract data type.
@@ -19,27 +22,24 @@ abstract class AbstractAuthorityBindingType extends AbstractSamlElement
     /**
      * Initialize a saml:AuthorityBindingType from scratch
      *
-     * @param string $AuthorityKind
-     * @param string $Location
-     * @param string $Binding
+     * @param \SimpleSAML\XML\Type\QNameValue $AuthorityKind
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $Location
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $Binding
      */
     final public function __construct(
-        protected string $AuthorityKind,
-        protected string $Location,
-        protected string $Binding,
+        protected QNameValue $AuthorityKind,
+        protected AnyURIValue $Location,
+        protected AnyURIValue $Binding,
     ) {
-        Assert::validQName($AuthorityKind);
-        Assert::validURI($Location);
-        Assert::validURI($Binding);
     }
 
 
     /**
      * Collect the value of the AuthorityKind-property
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getAuthorityKind(): string
+    public function getAuthorityKind(): QNameValue
     {
         return $this->AuthorityKind;
     }
@@ -48,9 +48,9 @@ public function getAuthorityKind(): string
     /**
      * Collect the value of the Location-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getLocation(): string
+    public function getLocation(): AnyURIValue
     {
         return $this->Location;
     }
@@ -59,9 +59,9 @@ public function getLocation(): string
     /**
      * Collect the value of the Binding-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getBinding(): string
+    public function getBinding(): AnyURIValue
     {
         return $this->Binding;
     }
@@ -81,9 +81,9 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $AuthorityKind = self::getAttribute($xml, 'AuthorityKind');
-        $Location = self::getAttribute($xml, 'Location');
-        $Binding = self::getAttribute($xml, 'Binding');
+        $AuthorityKind = self::getAttribute($xml, 'AuthorityKind', QNameValue::class);
+        $Location = self::getAttribute($xml, 'Location', AnyURIValue::class);
+        $Binding = self::getAttribute($xml, 'Binding', AnyURIValue::class);
 
         return new static($AuthorityKind, $Location, $Binding);
     }
@@ -99,11 +99,17 @@ public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
 
-        $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:samlp', C::NS_SAMLP);
-
-        $e->setAttribute('AuthorityKind', $this->getAuthorityKind());
-        $e->setAttribute('Location', $this->getLocation());
-        $e->setAttribute('Binding', $this->getBinding());
+        if (!$e->lookupPrefix($this->getAuthorityKind()->getNamespaceURI()->getValue())) {
+            $e->setAttributeNS(
+                'http://www.w3.org/2000/xmlns/',
+                'xmlns:' . $this->getAuthorityKind()->getNamespacePrefix()->getValue(),
+                $this->getAuthorityKind()->getNamespaceURI()->getValue(),
+            );
+        }
+
+        $e->setAttribute('AuthorityKind', strval($this->getAuthorityKind()));
+        $e->setAttribute('Location', strval($this->getLocation()));
+        $e->setAttribute('Binding', strval($this->getBinding()));
 
         return $e;
     }
diff --git a/src/SAML11/XML/saml/AbstractAuthorizationDecisionStatementType.php b/src/SAML11/XML/saml/AbstractAuthorizationDecisionStatementType.php
index 0306177..0e1a627 100644
--- a/src/SAML11/XML/saml/AbstractAuthorizationDecisionStatementType.php
+++ b/src/SAML11/XML/saml/AbstractAuthorizationDecisionStatementType.php
@@ -6,11 +6,16 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Assert\Assert as SAMLAssert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\XML\Exception\{
+    InvalidDOMElementException,
+    MissingElementException,
+    SchemaViolationException,
+    TooManyElementsException,
+};
+use SimpleSAML\XML\Type\AnyURIValue;
+
+use function strval;
 
 /**
  * SAML AuthorizationDecisionStatementType abstract data type.
@@ -22,7 +27,7 @@ abstract class AbstractAuthorizationDecisionStatementType extends AbstractSubjec
     /**
      * Initialize a saml:AuthorizationDecisionStatementType from scratch
      *
-     * @param string $resource
+     * @param \SimpleSAML\XML\Type\AnyURIValue $resource
      * @param \SimpleSAML\SAML11\XML\saml\DecisionTypeEnum $decision
      * @param \SimpleSAML\SAML11\XML\saml\Subject $subject
      * @param array<\SimpleSAML\SAML11\XML\saml\Action> $action
@@ -30,12 +35,12 @@ abstract class AbstractAuthorizationDecisionStatementType extends AbstractSubjec
      */
     final public function __construct(
         Subject $subject,
-        protected string $resource,
+        // Uses the base AnyURIValue because the SAML specification allows this attribute to be an empty string
+        protected AnyURIValue $resource,
         protected DecisionTypeEnum $decision,
         protected array $action = [],
         protected ?Evidence $evidence = null,
     ) {
-        SAMLAssert::validURI($resource);
         Assert::minCount($action, 1, MissingElementException::class);
         Assert::allIsInstanceOf($action, Action::class, SchemaViolationException::class);
 
@@ -46,9 +51,9 @@ final public function __construct(
     /**
      * Collect the value of the resource-property
      *
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getResource(): string
+    public function getResource(): AnyURIValue
     {
         return $this->resource;
     }
@@ -110,8 +115,10 @@ public static function fromXML(DOMElement $xml): static
 
         return new static(
             array_pop($subject),
-            self::getAttribute($xml, 'Resource'),
-            DecisionTypeEnum::from(self::getAttribute($xml, 'Decision')),
+            self::getAttribute($xml, 'Resource', AnyURIValue::class),
+            DecisionTypeEnum::from(
+                strval(self::getAttribute($xml, 'Decision', StringValue::class)),
+            ),
             Action::getChildrenOfClass($xml),
             array_pop($evidence),
         );
@@ -129,7 +136,7 @@ public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toXML($parent);
 
-        $e->setAttribute('Resource', $this->getResource());
+        $e->setAttribute('Resource', strval($this->getResource()));
         $e->setAttribute('Decision', $this->getDecision()->value);
 
         foreach ($this->getAction() as $action) {
diff --git a/src/SAML11/XML/saml/AbstractCondition.php b/src/SAML11/XML/saml/AbstractCondition.php
index add4b58..ed98e8a 100644
--- a/src/SAML11/XML/saml/AbstractCondition.php
+++ b/src/SAML11/XML/saml/AbstractCondition.php
@@ -8,17 +8,14 @@
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\Utils;
-use SimpleSAML\SAML11\XML\ExtensionPointInterface;
-use SimpleSAML\SAML11\XML\ExtensionPointTrait;
+use SimpleSAML\SAML11\XML\{ExtensionPointInterface, ExtensionPointTrait};
 use SimpleSAML\XML\Attribute as XMLAttribute;
 use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\QNameValue;
 
-use function count;
-use function explode;
+use function strval;
 
 /**
  * SAML Condition data type.
@@ -39,18 +36,18 @@ abstract class AbstractCondition extends AbstractConditionType implements
     /**
      * Initialize a custom saml:Condition element.
      *
-     * @param string $type
+     * @param \SimpleSAML\XML\Type\QNameValue $type
      */
     protected function __construct(
-        protected string $type,
+        protected QNameValue $type,
     ) {
     }
 
 
     /**
-     * @inheritDoc
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getXsiType(): string
+    public function getXsiType(): QNameValue
     {
         return $this->type;
     }
@@ -75,19 +72,7 @@ public static function fromXML(DOMElement $xml): static
             SchemaViolationException::class,
         );
 
-        $type = $xml->getAttributeNS(C::NS_XSI, 'type');
-        Assert::validQName($type, SchemaViolationException::class);
-
-        // first, try to resolve the type to a full namespaced version
-        $qname = explode(':', $type, 2);
-        if (count($qname) === 2) {
-            list($prefix, $element) = $qname;
-        } else {
-            $prefix = null;
-            list($element) = $qname;
-        }
-        $ns = $xml->lookupNamespaceUri($prefix);
-        $type = ($ns === null) ? $element : implode(':', [$ns, $element]);
+        $type = QNameValue::fromDocument($xml->getAttributeNS(C::NS_XSI, 'type'), $xml);
 
         // now check if we have a handler registered for it
         $handler = Utils::getContainer()->getExtensionHandler($type);
@@ -114,11 +99,14 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
-        $e->setAttributeNS(
-            'http://www.w3.org/2000/xmlns/',
-            'xmlns:' . static::getXsiTypePrefix(),
-            static::getXsiTypeNamespaceURI(),
-        );
+
+        if (!$e->lookupPrefix($this->getXsiType()->getNamespaceURI()->getValue())) {
+            $e->setAttributeNS(
+                'http://www.w3.org/2000/xmlns/',
+                'xmlns:' . static::getXsiTypePrefix(),
+                strval(static::getXsiTypeNamespaceURI()),
+            );
+        }
 
         $type = new XMLAttribute(C::NS_XSI, 'xsi', 'type', $this->getXsiType());
         $type->toXML($e);
diff --git a/src/SAML11/XML/saml/AbstractConditionsType.php b/src/SAML11/XML/saml/AbstractConditionsType.php
index 268bd91..eb432fa 100644
--- a/src/SAML11/XML/saml/AbstractConditionsType.php
+++ b/src/SAML11/XML/saml/AbstractConditionsType.php
@@ -4,14 +4,13 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Assert\Assert as SAMLAssert;
-use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Type\DateTimeValue;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 
+use function strval;
+
 /**
  * SAML ConditionsType abstract data type.
  *
@@ -25,15 +24,15 @@ abstract class AbstractConditionsType extends AbstractSamlElement
      * @param array<\SimpleSAML\SAML11\XML\saml\AudienceRestrictionCondition> $audienceRestrictionCondition
      * @param array<\SimpleSAML\SAML11\XML\saml\DoNotCacheCondition> $doNotCacheCondition
      * @param array<\SimpleSAML\SAML11\XML\saml\AbstractCondition> $condition
-     * @param \DateTimeImmutable|null $notBefore
-     * @param \DateTimeImmutable|null $notOnOrAfter
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue|null $notBefore
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue|null $notOnOrAfter
      */
     final public function __construct(
         protected array $audienceRestrictionCondition = [],
         protected array $doNotCacheCondition = [],
         protected array $condition = [],
-        protected ?DateTimeImmutable $notBefore = null,
-        protected ?DateTimeImmutable $notOnOrAfter = null,
+        protected ?DateTimeValue $notBefore = null,
+        protected ?DateTimeValue $notOnOrAfter = null,
     ) {
         Assert::allIsInstanceOf($audienceRestrictionCondition, AudienceRestrictionCondition::class);
         Assert::allIsInstanceOf($doNotCacheCondition, DoNotCacheCondition::class);
@@ -44,9 +43,9 @@ final public function __construct(
     /**
      * Collect the value of the notBefore-property
      *
-     * @return \DateTimeImmutable|null
+     * @return \SimpleSAML\SAML11\Type\DateTimeValue|null
      */
-    public function getNotBefore(): ?DateTimeImmutable
+    public function getNotBefore(): ?DateTimeValue
     {
         return $this->notBefore;
     }
@@ -55,9 +54,9 @@ public function getNotBefore(): ?DateTimeImmutable
     /**
      * Collect the value of the notOnOrAfter-property
      *
-     * @return \DateTimeImmutable|null
+     * @return \SimpleSAML\SAML11\Type\DateTimeValue|null
      */
-    public function getNotOnOrAfter(): ?DateTimeImmutable
+    public function getNotOnOrAfter(): ?DateTimeValue
     {
         return $this->notOnOrAfter;
     }
@@ -125,25 +124,13 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $notBefore = self::getOptionalAttribute($xml, 'NotBefore');
-        // Strip sub-seconds - See paragraph 1.2.2 of SAML core specifications
-        $notBefore = preg_replace('/([.][0-9]+Z)$/', 'Z', $notBefore, 1);
-
-        SAMLAssert::validDateTime($notBefore, ProtocolViolationException::class);
-        $notBefore = new DateTimeImmutable($notBefore);
-
-        $notOnOrAfter = self::getOptionalAttribute($xml, 'NotOnOrAfter');
-        // Strip sub-seconds - See paragraph 1.2.2 of SAML core specifications
-        $notOnOrAfter = preg_replace('/([.][0-9]+Z)$/', 'Z', $notOnOrAfter, 1);
-
-        SAMLAssert::validDateTime($notOnOrAfter, ProtocolViolationException::class);
-        $notOnOrAfter = new DateTimeImmutable($notOnOrAfter);
-
-        $audienceRestrictionCondition = AudienceRestrictionCondition::getChildrenOfClass($xml);
-        $doNotCacheCondition = DoNotCacheCondition::getChildrenOfClass($xml);
-        $condition = AbstractCondition::getChildrenOfClass($xml);
-
-        return new static($audienceRestrictionCondition, $doNotCacheCondition, $condition, $notBefore, $notOnOrAfter);
+        return new static(
+            AudienceRestrictionCondition::getChildrenOfClass($xml),
+            DoNotCacheCondition::getChildrenOfClass($xml),
+            AbstractCondition::getChildrenOfClass($xml),
+            self::getOptionalAttribute($xml, 'NotBefore', DateTimeValue::class),
+            self::getOptionalAttribute($xml, 'NotOnOrAfter', DateTimeValue::class),
+        );
     }
 
 
@@ -158,11 +145,11 @@ public function toXML(?DOMElement $parent = null): DOMElement
         $e = $this->instantiateParentElement($parent);
 
         if ($this->getNotBefore() !== null) {
-            $e->setAttribute('NotBefore', $this->getNotBefore()->format(C::DATETIME_FORMAT));
+            $e->setAttribute('NotBefore', strval($this->getNotBefore()));
         }
 
         if ($this->getNotOnOrAfter() !== null) {
-            $e->setAttribute('NotOnOrAfter', $this->getNotOnOrAfter()->format(C::DATETIME_FORMAT));
+            $e->setAttribute('NotOnOrAfter', strval($this->getNotOnOrAfter()));
         }
 
         foreach ($this->getAudienceRestrictionCondition() as $audienceRestrictionCondition) {
diff --git a/src/SAML11/XML/saml/AbstractEvidenceType.php b/src/SAML11/XML/saml/AbstractEvidenceType.php
index e985d45..4e72268 100644
--- a/src/SAML11/XML/saml/AbstractEvidenceType.php
+++ b/src/SAML11/XML/saml/AbstractEvidenceType.php
@@ -7,8 +7,7 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
 
 /**
  * SAML EvidenceType abstract data type.
diff --git a/src/SAML11/XML/saml/AbstractNameIdentifierType.php b/src/SAML11/XML/saml/AbstractNameIdentifierType.php
index 8bf7833..82f8a85 100644
--- a/src/SAML11/XML/saml/AbstractNameIdentifierType.php
+++ b/src/SAML11/XML/saml/AbstractNameIdentifierType.php
@@ -6,9 +6,11 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\StringElementTrait;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 
+use function strval;
+
 /**
  * SAML NameIdentifierType abstract data type.
  *
@@ -16,34 +18,38 @@
  */
 abstract class AbstractNameIdentifierType extends AbstractSamlElement
 {
-    use StringElementTrait;
-
-
     /**
      * Initialize a saml:NameIdentifierType from scratch
      *
-     * @param string $value
-     * @param string|null $Format
-     * @param string|null $NameQualifier
+     * @param \SimpleSAML\SAML11\Type\StringValue $value
+     * @param \SimpleSAML\SAML11\Type\StringValue|null $NameQualifier
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue|null $Format
      */
     final public function __construct(
-        string $value,
-        protected ?string $NameQualifier = null,
-        protected ?string $Format = null,
+        protected StringValue $value,
+        protected ?StringValue $NameQualifier = null,
+        protected ?AnyURIValue $Format = null,
     ) {
-        Assert::nullOrNotWhitespaceOnly($NameQualifier);
-        Assert::nullOrValidURI($Format); // Covers the empty string
+    }
+
 
-        $this->setContent($value);
+    /**
+     * Collect the value of the value-property
+     *
+     * @return \SimpleSAML\SAML11\Type\StringValue
+     */
+    public function getValue(): StringValue
+    {
+        return $this->value;
     }
 
 
     /**
      * Collect the value of the Format-property
      *
-     * @return string|null
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue|null
      */
-    public function getFormat(): ?string
+    public function getFormat(): ?AnyURIValue
     {
         return $this->Format;
     }
@@ -52,9 +58,9 @@ public function getFormat(): ?string
     /**
      * Collect the value of the NameQualifier-property
      *
-     * @return string|null
+     * @return \SimpleSAML\SAML11\Type\StringValue|null
      */
-    public function getNameQualifier(): ?string
+    public function getNameQualifier(): ?StringValue
     {
         return $this->NameQualifier;
     }
@@ -74,10 +80,11 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $NameQualifier = self::getOptionalAttribute($xml, 'NameQualifier', null);
-        $Format = self::getOptionalAttribute($xml, 'Format', null);
-
-        return new static($xml->textContent, $NameQualifier, $Format);
+        return new static(
+            StringValue::fromString($xml->textContent),
+            self::getOptionalAttribute($xml, 'NameQualifier', StringValue::class, null),
+            self::getOptionalAttribute($xml, 'Format', AnyURIValue::class, null),
+        );
     }
 
 
@@ -90,14 +97,14 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
-        $e->textContent = $this->getContent();
+        $e->textContent = strval($this->getValue());
 
         if ($this->getNameQualifier() !== null) {
-            $e->setAttribute('NameQualifier', $this->getNameQualifier());
+            $e->setAttribute('NameQualifier', strval($this->getNameQualifier()));
         }
 
         if ($this->getFormat() !== null) {
-            $e->setAttribute('Format', $this->getFormat());
+            $e->setAttribute('Format', strval($this->getFormat()));
         }
 
         return $e;
diff --git a/src/SAML11/XML/saml/AbstractStatement.php b/src/SAML11/XML/saml/AbstractStatement.php
index d56a895..c86f01b 100644
--- a/src/SAML11/XML/saml/AbstractStatement.php
+++ b/src/SAML11/XML/saml/AbstractStatement.php
@@ -8,17 +8,14 @@
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\Utils;
-use SimpleSAML\SAML11\XML\ExtensionPointInterface;
-use SimpleSAML\SAML11\XML\ExtensionPointTrait;
+use SimpleSAML\SAML11\XML\{ExtensionPointInterface, ExtensionPointTrait};
 use SimpleSAML\XML\Attribute as XMLAttribute;
 use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\QNameValue;
 
-use function count;
-use function explode;
+use function strval;
 
 /**
  * Class implementing the <saml:Statement> extension point.
@@ -39,18 +36,18 @@ abstract class AbstractStatement extends AbstractStatementType implements
     /**
      * Initialize a custom saml:Statement element.
      *
-     * @param string $type
+     * @param \SimpleSAML\XML\Type\QNameValue $type
      */
     protected function __construct(
-        protected string $type,
+        protected QNameValue $type,
     ) {
     }
 
 
     /**
-     * @inheritDoc
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getXsiType(): string
+    public function getXsiType(): QNameValue
     {
         return $this->type;
     }
@@ -75,19 +72,7 @@ public static function fromXML(DOMElement $xml): static
             SchemaViolationException::class,
         );
 
-        $type = $xml->getAttributeNS(C::NS_XSI, 'type');
-        Assert::validQName($type, SchemaViolationException::class);
-
-        // first, try to resolve the type to a full namespaced version
-        $qname = explode(':', $type, 2);
-        if (count($qname) === 2) {
-            list($prefix, $element) = $qname;
-        } else {
-            $prefix = null;
-            list($element) = $qname;
-        }
-        $ns = $xml->lookupNamespaceUri($prefix);
-        $type = ($ns === null) ? $element : implode(':', [$ns, $element]);
+        $type = QNameValue::fromDocument($xml->getAttributeNS(C::NS_XSI, 'type'), $xml);
 
         // now check if we have a handler registered for it
         $handler = Utils::getContainer()->getExtensionHandler($type);
@@ -114,11 +99,14 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
-        $e->setAttributeNS(
-            'http://www.w3.org/2000/xmlns/',
-            'xmlns:' . static::getXsiTypePrefix(),
-            static::getXsiTypeNamespaceURI(),
-        );
+
+        if (!$e->lookupPrefix($this->getXsiType()->getNamespaceURI()->getValue())) {
+            $e->setAttributeNS(
+                'http://www.w3.org/2000/xmlns/',
+                'xmlns:' . static::getXsiTypePrefix(),
+                strval(static::getXsiTypeNamespaceURI()),
+            );
+        }
 
         $type = new XMLAttribute(C::NS_XSI, 'xsi', 'type', $this->getXsiType());
         $type->toXML($e);
diff --git a/src/SAML11/XML/saml/AbstractSubjectConfirmationType.php b/src/SAML11/XML/saml/AbstractSubjectConfirmationType.php
index 4dd8e37..357dca4 100644
--- a/src/SAML11/XML/saml/AbstractSubjectConfirmationType.php
+++ b/src/SAML11/XML/saml/AbstractSubjectConfirmationType.php
@@ -6,10 +6,12 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\XML\Exception\{
+    InvalidDOMElementException,
+    MissingElementException,
+    SchemaViolationException,
+    TooManyElementsException,
+};
 use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
 
 /**
diff --git a/src/SAML11/XML/saml/AbstractSubjectLocalityType.php b/src/SAML11/XML/saml/AbstractSubjectLocalityType.php
index bf849ea..5ee8f1c 100644
--- a/src/SAML11/XML/saml/AbstractSubjectLocalityType.php
+++ b/src/SAML11/XML/saml/AbstractSubjectLocalityType.php
@@ -6,8 +6,11 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML11\Type\StringValue;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 
+use function strval;
+
 /**
  * SAML SubjectLocalityType abstract data type.
  *
@@ -18,24 +21,22 @@ abstract class AbstractSubjectLocalityType extends AbstractSamlElement
     /**
      * Initialize a saml:SubjectLocalityType from scratch
      *
-     * @param string|null $IPAddress
-     * @param string|null $DNSAddress
+     * @param \SimpleSAML\SAML11\Type\StringValue|null $IPAddress
+     * @param \SimpleSAML\SAML11\Type\StringValue|null $DNSAddress
      */
     final public function __construct(
-        protected ?string $IPAddress = null,
-        protected ?string $DNSAddress = null,
+        protected ?StringValue $IPAddress = null,
+        protected ?StringValue $DNSAddress = null,
     ) {
-        Assert::nullOrNotWhitespaceOnly($IPAddress);
-        Assert::nullOrNotWhitespaceOnly($DNSAddress);
     }
 
 
     /**
      * Collect the value of the IPAddress-property
      *
-     * @return string|null
+     * @return \SimpleSAML\SAML11\Type\StringValue|null
      */
-    public function getIPAddress(): ?string
+    public function getIPAddress(): ?StringValue
     {
         return $this->IPAddress;
     }
@@ -44,9 +45,9 @@ public function getIPAddress(): ?string
     /**
      * Collect the value of the DNSAddress-property
      *
-     * @return string|null
+     * @return \SimpleSAML\SAML11\Type\StringValue|null
      */
-    public function getDNSAddress(): ?string
+    public function getDNSAddress(): ?StringValue
     {
         return $this->DNSAddress;
     }
@@ -78,8 +79,8 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $IPAddress = self::getOptionalAttribute($xml, 'IPAddress');
-        $DNSAddress = self::getOptionalAttribute($xml, 'DNSAddress');
+        $IPAddress = self::getOptionalAttribute($xml, 'IPAddress', StringValue::class);
+        $DNSAddress = self::getOptionalAttribute($xml, 'DNSAddress', StringValue::class);
 
         return new static($IPAddress, $DNSAddress);
     }
@@ -96,11 +97,11 @@ public function toXML(?DOMElement $parent = null): DOMElement
         $e = $this->instantiateParentElement($parent);
 
         if ($this->getIPAddress() !== null) {
-            $e->setAttribute('IPAddress', $this->getIPAddress());
+            $e->setAttribute('IPAddress', strval($this->getIPAddress()));
         }
 
         if ($this->getDNSAddress() !== null) {
-            $e->setAttribute('DNSAddress', $this->getDNSAddress());
+            $e->setAttribute('DNSAddress', strval($this->getDNSAddress()));
         }
 
         return $e;
diff --git a/src/SAML11/XML/saml/AbstractSubjectStatement.php b/src/SAML11/XML/saml/AbstractSubjectStatement.php
index ff4e70d..d4d8673 100644
--- a/src/SAML11/XML/saml/AbstractSubjectStatement.php
+++ b/src/SAML11/XML/saml/AbstractSubjectStatement.php
@@ -8,17 +8,16 @@
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\Utils;
-use SimpleSAML\SAML11\XML\ExtensionPointInterface;
-use SimpleSAML\SAML11\XML\ExtensionPointTrait;
+use SimpleSAML\SAML11\XML\{ExtensionPointInterface, ExtensionPointTrait};
 use SimpleSAML\XML\Attribute as XMLAttribute;
 use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
-
-use function count;
-use function explode;
+use SimpleSAML\XML\Exception\{
+    InvalidDOMElementException,
+    MissingElementException,
+    SchemaViolationException,
+    TooManyElementsException,
+};
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Class implementing the <saml:SubjectStatement> extension point.
@@ -36,10 +35,10 @@ abstract class AbstractSubjectStatement extends AbstractSubjectStatementType imp
     /**
      * Initialize a custom saml:SubjectStatement element.
      *
-     * @param string $type
+     * @param \SimpleSAML\XML\Type\QNameValue $type
      */
     protected function __construct(
-        protected string $type,
+        protected QNameValue $type,
         Subject $subject,
     ) {
         parent::__construct($subject);
@@ -47,9 +46,9 @@ protected function __construct(
 
 
     /**
-     * @inheritDoc
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getXsiType(): string
+    public function getXsiType(): QNameValue
     {
         return $this->type;
     }
@@ -74,19 +73,7 @@ public static function fromXML(DOMElement $xml): static
             SchemaViolationException::class,
         );
 
-        $type = $xml->getAttributeNS(C::NS_XSI, 'type');
-        Assert::validQName($type, SchemaViolationException::class);
-
-        // first, try to resolve the type to a full namespaced version
-        $qname = explode(':', $type, 2);
-        if (count($qname) === 2) {
-            list($prefix, $element) = $qname;
-        } else {
-            $prefix = null;
-            list($element) = $qname;
-        }
-        $ns = $xml->lookupNamespaceUri($prefix);
-        $type = ($ns === null) ? $element : implode(':', [$ns, $element]);
+        $type = QNameValue::fromDocument($xml->getAttributeNS(C::NS_XSI, 'type'), $xml);
 
         // now check if we have a handler registered for it
         $handler = Utils::getContainer()->getExtensionHandler($type);
@@ -117,11 +104,14 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toXML($parent);
-        $e->setAttributeNS(
-            'http://www.w3.org/2000/xmlns/',
-            'xmlns:' . static::getXsiTypePrefix(),
-            static::getXsiTypeNamespaceURI(),
-        );
+
+        if (!$e->lookupPrefix($this->getXsiType()->getNamespaceURI()->getValue())) {
+            $e->setAttributeNS(
+                'http://www.w3.org/2000/xmlns/',
+                'xmlns:' . static::getXsiTypePrefix(),
+                static::getXsiTypeNamespaceURI()->getValue(),
+            );
+        }
 
         $type = new XMLAttribute(C::NS_XSI, 'xsi', 'type', $this->getXsiType());
         $type->toXML($e);
diff --git a/src/SAML11/XML/saml/AbstractSubjectStatementType.php b/src/SAML11/XML/saml/AbstractSubjectStatementType.php
index 3ab1983..96b2058 100644
--- a/src/SAML11/XML/saml/AbstractSubjectStatementType.php
+++ b/src/SAML11/XML/saml/AbstractSubjectStatementType.php
@@ -5,8 +5,6 @@
 namespace SimpleSAML\SAML11\XML\saml;
 
 use DOMElement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatementType;
-use SimpleSAML\SAML11\XML\saml\Subject;
 
 /**
  * @package simplesamlphp\saml11
diff --git a/src/SAML11/XML/saml/AbstractSubjectType.php b/src/SAML11/XML/saml/AbstractSubjectType.php
index b669ca1..f1ce423 100644
--- a/src/SAML11/XML/saml/AbstractSubjectType.php
+++ b/src/SAML11/XML/saml/AbstractSubjectType.php
@@ -6,9 +6,7 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
 
 /**
  * SAML SubjectType abstract data type.
diff --git a/src/SAML11/XML/saml/Action.php b/src/SAML11/XML/saml/Action.php
index a705f5c..381858a 100644
--- a/src/SAML11/XML/saml/Action.php
+++ b/src/SAML11/XML/saml/Action.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Action element.
diff --git a/src/SAML11/XML/saml/Advice.php b/src/SAML11/XML/saml/Advice.php
index a904159..aa5d8e2 100644
--- a/src/SAML11/XML/saml/Advice.php
+++ b/src/SAML11/XML/saml/Advice.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Advice element.
diff --git a/src/SAML11/XML/saml/Assertion.php b/src/SAML11/XML/saml/Assertion.php
index dab25e4..1aa1092 100644
--- a/src/SAML11/XML/saml/Assertion.php
+++ b/src/SAML11/XML/saml/Assertion.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Assertion element.
diff --git a/src/SAML11/XML/saml/AssertionIDReference.php b/src/SAML11/XML/saml/AssertionIDReference.php
index 45bcfd6..12d48db 100644
--- a/src/SAML11/XML/saml/AssertionIDReference.php
+++ b/src/SAML11/XML/saml/AssertionIDReference.php
@@ -4,13 +4,9 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use DOMElement;
-use SimpleSAML\SAML11\Assert\Assert;
-use SimpleSAML\SAML11\XML\StringElementTrait;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\NCNameValue;
+use SimpleSAML\XML\TypedTextContentTrait;
 
 /**
  * Class representing a saml:AssertionIDReference element.
@@ -20,60 +16,8 @@
 final class AssertionIDReference extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use TypedTextContentTrait;
 
-
-    /**
-     * @param string $content
-     */
-    public function __construct(string $content)
-    {
-        $this->setContent($content);
-    }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::validNCName($content, SchemaViolationException::class); // Covers the empty string
-    }
-
-
-    /**
-     * Convert XML into an AssertionIDReference
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
-
-
-    /**
-     * Convert this AssertionIDReference to XML.
-     *
-     * @param \DOMElement $parent The element we are converting to XML.
-     * @return \DOMElement The XML element after adding the data corresponding to this AssertionIDReference.
-     */
-    public function toXML(?DOMElement $parent = null): DOMElement
-    {
-        $element = $this->instantiateParentElement($parent);
-        $element->textContent = $this->getContent();
-
-        return $element;
-    }
+    /** @var string */
+    public const TEXTCONTENT_TYPE = NCNameValue::class;
 }
diff --git a/src/SAML11/XML/saml/Attribute.php b/src/SAML11/XML/saml/Attribute.php
index 5c13916..e16e225 100644
--- a/src/SAML11/XML/saml/Attribute.php
+++ b/src/SAML11/XML/saml/Attribute.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Attribute element.
diff --git a/src/SAML11/XML/saml/AttributeDesignator.php b/src/SAML11/XML/saml/AttributeDesignator.php
index bb4297e..3c30a5e 100644
--- a/src/SAML11/XML/saml/AttributeDesignator.php
+++ b/src/SAML11/XML/saml/AttributeDesignator.php
@@ -6,9 +6,9 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:AttributeDesignator element.
@@ -33,9 +33,9 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
 
-        $AttributeName = self::getAttribute($xml, 'AttributeName');
-        $AttributeNamespace = self::getAttribute($xml, 'AttributeNamespace');
-
-        return new static($AttributeName, $AttributeNamespace);
+        return new static(
+            self::getAttribute($xml, 'AttributeName', StringValue::class),
+            self::getAttribute($xml, 'AttributeNamespace', AnyURIValue::class),
+        );
     }
 }
diff --git a/src/SAML11/XML/saml/AttributeStatement.php b/src/SAML11/XML/saml/AttributeStatement.php
index 86cb38a..92b3322 100644
--- a/src/SAML11/XML/saml/AttributeStatement.php
+++ b/src/SAML11/XML/saml/AttributeStatement.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:AttributeStatement element.
diff --git a/src/SAML11/XML/saml/AttributeValue.php b/src/SAML11/XML/saml/AttributeValue.php
index b5275c4..a23c33b 100644
--- a/src/SAML11/XML/saml/AttributeValue.php
+++ b/src/SAML11/XML/saml/AttributeValue.php
@@ -4,21 +4,19 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use DateTimeImmutable;
-use DateTimeInterface;
 use DOMElement;
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
+use SimpleSAML\SAML11\Type\{DateTimeValue, StringValue};
 use SimpleSAML\XML\AbstractElement;
 use SimpleSAML\XML\Chunk;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\{IntegerValue, ValueTypeInterface};
 
 use function class_exists;
 use function explode;
 use function gettype;
-use function intval;
 use function str_contains;
 use function strval;
 
@@ -34,16 +32,11 @@ class AttributeValue extends AbstractSamlElement implements SchemaValidatableEle
     /**
      * Create an AttributeValue.
      *
-     * The value of this element. Can be one of:
-     *  - string
-     *  - int
-     *  - \SimpleSAML\XML\AbstractElement
-     *
-     * @param string|int|\DateTimeInterface|\SimpleSAML\XML\AbstractElement $value
+     * @param \SimpleSAML\XML\Type\ValueTypeInterface|\SimpleSAML\XML\AbstractElement $value
      * @throws \SimpleSAML\Assert\AssertionFailedException if the supplied value is neither a string or a DOMElement
      */
     final public function __construct(
-        protected string|int|DateTimeInterface|AbstractElement $value,
+        protected StringValue|IntegerValue|DateTimeValue|AbstractElement $value,
     ) {
     }
 
@@ -56,23 +49,17 @@ final public function __construct(
     public function getXsiType(): string
     {
         $value = $this->getValue();
-        $type = gettype($value);
-
-        switch ($type) {
-            case "integer":
-                return "xs:integer";
-            case "object":
-                if ($value instanceof DateTimeInterface) {
-                    return 'xs:dateTime';
-                }
 
-                return sprintf(
-                    '%s:%s',
-                    $this->value::getNamespacePrefix(),
-                    AbstractElement::getClassName(get_class($value)),
-                );
-            default:
-                return "xs:string";
+        if ($value === null) {
+            return 'xs:nil';
+        } elseif ($value instanceof ValueTypeInterface) {
+            return $value::SCHEMA_NAMESPACE_PREFIX . ':' . $value::SCHEMA_TYPE;
+        } else {
+            return sprintf(
+                '%s:%s',
+                $value::getNamespacePrefix(),
+                $value::getLocalName(),
+            );
         }
     }
 
@@ -80,7 +67,13 @@ public function getXsiType(): string
     /**
      * Get this attribute value.
      *
-     * @return string|int|\SimpleSAML\XML\AbstractElement[]|null
+     * @return (
+     *   \SimpleSAML\XML\Type\IntegerValue|
+     *   \SimpleSAML\SAML11\Type\StringValue|
+     *   \SimpleSAML\SAML11\Type\DateTimeValue|
+     *   \SimpleSAML\XML\AbstractElement|
+     *   null
+     * )
      */
     public function getValue()
     {
@@ -121,10 +114,8 @@ public static function fromXML(DOMElement $xml): static
             $xml->hasAttributeNS(C::NS_XSI, "type") &&
             $xml->getAttributeNS(C::NS_XSI, "type") === "xs:integer"
         ) {
-            Assert::numeric($xml->textContent);
-
             // we have an integer as value
-            $value = intval($xml->textContent);
+            $value = IntegerValue::fromString($xml->textContent);
         } elseif (
             $xml->hasAttributeNS(C::NS_XSI, "nil") &&
             ($xml->getAttributeNS(C::NS_XSI, "nil") === "1" || $xml->getAttributeNS(C::NS_XSI, "nil") === "true")
@@ -135,12 +126,10 @@ public static function fromXML(DOMElement $xml): static
             $xml->hasAttributeNS(C::NS_XSI, "type") &&
             $xml->getAttributeNS(C::NS_XSI, "type") === "xs:dateTime"
         ) {
-            Assert::validDateTime($xml->textContent);
-
             // we have a dateTime as value
-            $value = new DateTimeImmutable($xml->textContent);
+            $value = DateTimeValue::fromString($xml->textContent);
         } else {
-            $value = $xml->textContent;
+            $value = StringValue::fromString($xml->textContent);
         }
 
         return new static($value);
@@ -162,7 +151,7 @@ public function toXML(?DOMElement $parent = null): DOMElement
         $type = gettype($value);
 
         switch ($type) {
-            case "integer":
+            case IntegerValue::class:
                 // make sure that the xs namespace is available in the AttributeValue
                 $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xsi', C::NS_XSI);
                 $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xs', C::NS_XS);
@@ -170,17 +159,24 @@ public function toXML(?DOMElement $parent = null): DOMElement
                 $e->textContent = strval($value);
                 break;
             case "object":
-                if ($value instanceof DateTimeInterface) {
+                if ($value instanceof DateTimeValue) {
                     $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xsi', C::NS_XSI);
                     $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xs', C::NS_XS);
                     $e->setAttributeNS(C::NS_XSI, 'xsi:type', 'xs:dateTime');
-                    $e->textContent = $value->format(C::DATETIME_FORMAT);
+                    $e->textContent = strval($value);
+                } elseif ($value instanceof ValueTypeInterface) {
+                    if ($value instanceof IntegerValue) {
+                        $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xsi', C::NS_XSI);
+                        $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xs', C::NS_XS);
+                        $e->setAttributeNS(C::NS_XSI, 'xsi:type', 'xs:integer');
+                    }
+                    $e->textContent = strval($value);
                 } else {
                     $value->toXML($e);
                 }
                 break;
             default: // string
-                $e->textContent = $value;
+                $e->textContent = strval($value);
                 break;
         }
 
diff --git a/src/SAML11/XML/saml/Audience.php b/src/SAML11/XML/saml/Audience.php
index 867a4da..b4bc74e 100644
--- a/src/SAML11/XML/saml/Audience.php
+++ b/src/SAML11/XML/saml/Audience.php
@@ -4,9 +4,9 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\SAML11\XML\URIElementTrait;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\TypedTextContentTrait;
 
 /**
  * SAML Audience element.
@@ -16,17 +16,8 @@
 final class Audience extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use URIElementTrait;
+    use TypedTextContentTrait;
 
-
-    /**
-     * Initialize a saml:Audience from scratch
-     *
-     * @param string $value
-     */
-    public function __construct(
-        protected string $value,
-    ) {
-        $this->setContent($value);
-    }
+    /** @var string */
+    public const TEXTCONTENT_TYPE = AnyURIValue::class;
 }
diff --git a/src/SAML11/XML/saml/AudienceRestrictionCondition.php b/src/SAML11/XML/saml/AudienceRestrictionCondition.php
index 5c34a62..e5be5a2 100644
--- a/src/SAML11/XML/saml/AudienceRestrictionCondition.php
+++ b/src/SAML11/XML/saml/AudienceRestrictionCondition.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:AudienceRestrictionCondition element.
diff --git a/src/SAML11/XML/saml/AuthenticationStatement.php b/src/SAML11/XML/saml/AuthenticationStatement.php
index 3aa0a20..d3511dd 100644
--- a/src/SAML11/XML/saml/AuthenticationStatement.php
+++ b/src/SAML11/XML/saml/AuthenticationStatement.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:AuthenticationStatement element.
diff --git a/src/SAML11/XML/saml/AuthorityBinding.php b/src/SAML11/XML/saml/AuthorityBinding.php
index ddf1951..5f786e3 100644
--- a/src/SAML11/XML/saml/AuthorityBinding.php
+++ b/src/SAML11/XML/saml/AuthorityBinding.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:AuthorityBinding element.
diff --git a/src/SAML11/XML/saml/AuthorizationDecisionStatement.php b/src/SAML11/XML/saml/AuthorizationDecisionStatement.php
index 606f1cf..48006e4 100644
--- a/src/SAML11/XML/saml/AuthorizationDecisionStatement.php
+++ b/src/SAML11/XML/saml/AuthorizationDecisionStatement.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:AuthorizationDecisionStatement element.
diff --git a/src/SAML11/XML/saml/Conditions.php b/src/SAML11/XML/saml/Conditions.php
index c99ae9c..e0d230c 100644
--- a/src/SAML11/XML/saml/Conditions.php
+++ b/src/SAML11/XML/saml/Conditions.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Conditions element.
diff --git a/src/SAML11/XML/saml/ConfirmationMethod.php b/src/SAML11/XML/saml/ConfirmationMethod.php
index 5ea50b4..774a63a 100644
--- a/src/SAML11/XML/saml/ConfirmationMethod.php
+++ b/src/SAML11/XML/saml/ConfirmationMethod.php
@@ -4,9 +4,9 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\SAML11\XML\URIElementTrait;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\TypedTextContentTrait;
 
 /**
  * Class representing a saml:ConfirmationMethod element.
@@ -16,14 +16,8 @@
 final class ConfirmationMethod extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use URIElementTrait;
+    use TypedTextContentTrait;
 
-
-    /**
-     * @param string $content
-     */
-    public function __construct(string $content)
-    {
-        $this->setContent($content);
-    }
+    /** @var string */
+    public const TEXTCONTENT_TYPE = AnyURIValue::class;
 }
diff --git a/src/SAML11/XML/saml/DoNotCacheCondition.php b/src/SAML11/XML/saml/DoNotCacheCondition.php
index e16abc5..44f8a76 100644
--- a/src/SAML11/XML/saml/DoNotCacheCondition.php
+++ b/src/SAML11/XML/saml/DoNotCacheCondition.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:DoNotCacheCondition element.
diff --git a/src/SAML11/XML/saml/Evidence.php b/src/SAML11/XML/saml/Evidence.php
index c88e852..3f95306 100644
--- a/src/SAML11/XML/saml/Evidence.php
+++ b/src/SAML11/XML/saml/Evidence.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Evidence element.
diff --git a/src/SAML11/XML/saml/NameIdentifier.php b/src/SAML11/XML/saml/NameIdentifier.php
index 3694c9d..34773ba 100644
--- a/src/SAML11/XML/saml/NameIdentifier.php
+++ b/src/SAML11/XML/saml/NameIdentifier.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:NameIdentifier element.
diff --git a/src/SAML11/XML/saml/Subject.php b/src/SAML11/XML/saml/Subject.php
index edcf6f0..fcec36c 100644
--- a/src/SAML11/XML/saml/Subject.php
+++ b/src/SAML11/XML/saml/Subject.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:Subject element.
diff --git a/src/SAML11/XML/saml/SubjectConfirmation.php b/src/SAML11/XML/saml/SubjectConfirmation.php
index dce23bf..04d1fe3 100644
--- a/src/SAML11/XML/saml/SubjectConfirmation.php
+++ b/src/SAML11/XML/saml/SubjectConfirmation.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:SubjectConfirmation element.
diff --git a/src/SAML11/XML/saml/SubjectConfirmationData.php b/src/SAML11/XML/saml/SubjectConfirmationData.php
index 14f6562..0184a18 100644
--- a/src/SAML11/XML/saml/SubjectConfirmationData.php
+++ b/src/SAML11/XML/saml/SubjectConfirmationData.php
@@ -7,16 +7,16 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
+use SimpleSAML\SAML11\Type\StringValue;
 use SimpleSAML\XML\AbstractElement;
 use SimpleSAML\XML\Chunk;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\{IntegerValue, ValueTypeInterface};
 
 use function class_exists;
 use function explode;
 use function gettype;
-use function intval;
 use function str_contains;
 use function strval;
 
@@ -33,15 +33,15 @@ class SubjectConfirmationData extends AbstractSamlElement implements SchemaValid
      * Create an SubjectConfirmationData.
      *
      * @param mixed $value The value of this element. Can be one of:
-     *  - string
-     *  - int
+     *  - \SimpleSAML\XML\Type\IntegerValue
+     *  - \SimpleSAML\SAML11\Type\StringValue
      *  - null
      *  - \SimpleSAML\XML\AbstractElement
      *
      * @throws \SimpleSAML\Assert\AssertionFailedException if the supplied value is neither a string or a DOMElement
      */
     final public function __construct(
-        protected string|int|null|AbstractElement $value,
+        protected StringValue|IntegerValue|null|AbstractElement $value,
     ) {
     }
 
@@ -53,21 +53,18 @@ final public function __construct(
      */
     public function getXsiType(): string
     {
-        $type = gettype($this->value);
+        $value = $this->getValue();
 
-        switch ($type) {
-            case "integer":
-                return "xs:integer";
-            case "NULL":
-                return "xs:nil";
-            case "object":
-                return sprintf(
-                    '%s:%s',
-                    $this->value::getNamespacePrefix(),
-                    AbstractElement::getClassName(get_class($this->value)),
-                );
-            default:
-                return "xs:string";
+        if ($value === null) {
+            return 'xs:nil';
+        } elseif ($value instanceof ValueTypeInterface) {
+            return $value::SCHEMA_NAMESPACE_PREFIX . ':' . $value::SCHEMA_TYPE;
+        } else {
+            return sprintf(
+                '%s:%s',
+                $value::getNamespacePrefix(),
+                $value::getLocalName(),
+            );
         }
     }
 
@@ -77,7 +74,7 @@ public function getXsiType(): string
      *
      * @return string|int|\SimpleSAML\XML\AbstractElement[]|null
      */
-    public function getValue()
+    public function getValue(): StringValue|IntegerValue|AbstractElement|null
     {
         return $this->value;
     }
@@ -117,7 +114,7 @@ public static function fromXML(DOMElement $xml): static
             $xml->getAttributeNS(C::NS_XSI, "type") === "xs:integer"
         ) {
             // we have an integer as value
-            $value = intval($xml->textContent);
+            $value = IntegerValue::fromString($xml->textContent);
         } elseif (
             // null value
             $xml->hasAttributeNS(C::NS_XSI, "nil") &&
@@ -126,7 +123,7 @@ public static function fromXML(DOMElement $xml): static
         ) {
             $value = null;
         } else {
-            $value = $xml->textContent;
+            $value = StringValue::fromString($xml->textContent);
         }
 
         return new static($value);
@@ -144,7 +141,8 @@ public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::instantiateParentElement($parent);
 
-        $type = gettype($this->value);
+        $value = $this->getValue();
+        $type = gettype($value);
 
         switch ($type) {
             case "integer":
@@ -152,7 +150,7 @@ public function toXML(?DOMElement $parent = null): DOMElement
                 $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xsi', C::NS_XSI);
                 $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xs', C::NS_XS);
                 $e->setAttributeNS(C::NS_XSI, 'xsi:type', 'xs:integer');
-                $e->textContent = strval($this->getValue());
+                $e->textContent = strval($value);
                 break;
             case "NULL":
                 $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xsi', C::NS_XSI);
@@ -160,10 +158,19 @@ public function toXML(?DOMElement $parent = null): DOMElement
                 $e->textContent = '';
                 break;
             case "object":
-                $this->getValue()->toXML($e);
+                if ($value instanceof ValueTypeInterface) {
+                    if ($this->value instanceof IntegerValue) {
+                        $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xsi', C::NS_XSI);
+                        $e->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:xs', C::NS_XS);
+                        $e->setAttributeNS(C::NS_XSI, 'xsi:type', 'xs:integer');
+                    }
+                    $e->textContent = strval($value);
+                } else {
+                    $value->toXML($e);
+                }
                 break;
             default: // string
-                $e->textContent = $this->getValue();
+                $e->textContent = strval($value);
                 break;
         }
 
diff --git a/src/SAML11/XML/saml/SubjectLocality.php b/src/SAML11/XML/saml/SubjectLocality.php
index f2b46f7..987d4c8 100644
--- a/src/SAML11/XML/saml/SubjectLocality.php
+++ b/src/SAML11/XML/saml/SubjectLocality.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\saml;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:SubjectLocality element.
diff --git a/src/SAML11/XML/saml/UnknownCondition.php b/src/SAML11/XML/saml/UnknownCondition.php
index 21ba8ef..fbccc3e 100644
--- a/src/SAML11/XML/saml/UnknownCondition.php
+++ b/src/SAML11/XML/saml/UnknownCondition.php
@@ -6,6 +6,7 @@
 
 use DOMElement;
 use SimpleSAML\XML\Chunk;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Class for unknown conditions.
@@ -16,11 +17,11 @@ final class UnknownCondition extends AbstractCondition
 {
     /**
      * @param \SimpleSAML\XML\Chunk $chunk The whole Condition element as a chunk object.
-     * @param string $type The xsi:type of this condition.
+     * @param \SimpleSAML\XML\Type\QNameValue $type The xsi:type of this condition.
      */
     public function __construct(
         protected Chunk $chunk,
-        string $type,
+        QNameValue $type,
     ) {
         parent::__construct($type);
     }
diff --git a/src/SAML11/XML/saml/UnknownStatement.php b/src/SAML11/XML/saml/UnknownStatement.php
index 8721a85..50173bb 100644
--- a/src/SAML11/XML/saml/UnknownStatement.php
+++ b/src/SAML11/XML/saml/UnknownStatement.php
@@ -6,6 +6,7 @@
 
 use DOMElement;
 use SimpleSAML\XML\Chunk;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Class for unknown statements.
@@ -16,11 +17,11 @@ final class UnknownStatement extends AbstractStatement
 {
     /**
      * @param \SimpleSAML\XML\Chunk $chunk The whole Statement element as a chunk object.
-     * @param string $type The xsi:type of this statement
+     * @param \SimpleSAML\XML\Type\QNameValue $type The xsi:type of this statement
      */
     public function __construct(
         protected Chunk $chunk,
-        string $type,
+        QNameValue $type,
     ) {
         parent::__construct($type);
     }
diff --git a/src/SAML11/XML/saml/UnknownSubjectStatement.php b/src/SAML11/XML/saml/UnknownSubjectStatement.php
index 4e593e2..38fb511 100644
--- a/src/SAML11/XML/saml/UnknownSubjectStatement.php
+++ b/src/SAML11/XML/saml/UnknownSubjectStatement.php
@@ -6,6 +6,7 @@
 
 use DOMElement;
 use SimpleSAML\XML\Chunk;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Class for unknown SubjectStatements.
@@ -16,11 +17,11 @@ final class UnknownSubjectStatement extends AbstractSubjectStatement
 {
     /**
      * @param \SimpleSAML\XML\Chunk $chunk The whole SubjectStatement element as a chunk object.
-     * @param string $type The xsi:type of this SubjectStatement
+     * @param \SimpleSAML\XML\Type\QNameValue $type The xsi:type of this SubjectStatement
      */
     public function __construct(
         protected Chunk $chunk,
-        string $type,
+        QNameValue $type,
         protected Subject $subject,
     ) {
         parent::__construct($type, $subject);
diff --git a/src/SAML11/XML/samlp/AbstractAttributeQueryType.php b/src/SAML11/XML/samlp/AbstractAttributeQueryType.php
index 0016863..7f812b7 100644
--- a/src/SAML11/XML/samlp/AbstractAttributeQueryType.php
+++ b/src/SAML11/XML/samlp/AbstractAttributeQueryType.php
@@ -6,10 +6,12 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\saml\AttributeDesignator;
-use SimpleSAML\SAML11\XML\saml\Subject;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{AttributeDesignator, Subject};
 use SimpleSAML\XML\Exception\SchemaViolationException;
 
+use function strval;
+
 /**
  * Abstract class to be implemented by all the attributes queries in this namespace
  *
@@ -21,15 +23,14 @@ abstract class AbstractAttributeQueryType extends AbstractSubjectQueryAbstractTy
      * Initialize a samlp:AttributeQuery element.
      *
      * @param \SimpleSAML\SAML11\XML\saml\Subject $subject
-     * @param string|null $resource
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue|null $resource
      * @param array<\SimpleSAML\SAML11\XML\saml\AttributeDesignator> $attributeDesignator
      */
     public function __construct(
         Subject $subject,
-        protected ?string $resource = null,
+        protected ?AnyURIValue $resource = null,
         protected array $attributeDesignator = [],
     ) {
-        Assert::nullOrValidURI($resource, SchemaViolationException::class);
         Assert::allIsInstanceOf($attributeDesignator, AttributeDesignator::class, SchemaViolationException::class);
 
         parent::__construct($subject);
@@ -37,9 +38,9 @@ public function __construct(
 
 
     /**
-     * @return string|null
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue|null
      */
-    public function getResource(): ?string
+    public function getResource(): ?AnyURIValue
     {
         return $this->resource;
     }
@@ -65,7 +66,7 @@ public function toXML(?DOMElement $parent = null): DOMElement
         $e = parent::toXML($parent);
 
         if ($this->getResource() !== null) {
-            $e->setAttribute('Resource', $this->getResource());
+            $e->setAttribute('Resource', strval($this->getResource()));
         }
 
         foreach ($this->getAttributeDesignator() as $attrDesignator) {
diff --git a/src/SAML11/XML/samlp/AbstractAuthenticationQueryType.php b/src/SAML11/XML/samlp/AbstractAuthenticationQueryType.php
index 8f2ada4..bec0b47 100644
--- a/src/SAML11/XML/samlp/AbstractAuthenticationQueryType.php
+++ b/src/SAML11/XML/samlp/AbstractAuthenticationQueryType.php
@@ -5,9 +5,10 @@
 namespace SimpleSAML\SAML11\XML\samlp;
 
 use DOMElement;
-use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML11\Type\AnyURIValue;
 use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+
+use function strval;
 
 /**
  * Abstract class to be implemented by all the authentication queries in this namespace
@@ -20,22 +21,20 @@ abstract class AbstractAuthenticationQueryType extends AbstractSubjectQueryAbstr
      * Initialize a samlp:AuthenticationQuery element.
      *
      * @param \SimpleSAML\SAML11\XML\saml\Subject $subject
-     * @param string $authenticationMethod
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $authenticationMethod
      */
     public function __construct(
         Subject $subject,
-        protected string $authenticationMethod,
+        protected AnyURIValue $authenticationMethod,
     ) {
-        Assert::validURI($authenticationMethod, SchemaViolationException::class);
-
         parent::__construct($subject);
     }
 
 
     /**
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getAuthenticationMethod(): string
+    public function getAuthenticationMethod(): AnyURIValue
     {
         return $this->authenticationMethod;
     }
@@ -50,7 +49,7 @@ public function getAuthenticationMethod(): string
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toXML($parent);
-        $e->setAttribute('AuthenticationMethod', $this->getAuthenticationMethod());
+        $e->setAttribute('AuthenticationMethod', strval($this->getAuthenticationMethod()));
 
         return $e;
     }
diff --git a/src/SAML11/XML/samlp/AbstractAuthorizationDecisionQueryType.php b/src/SAML11/XML/samlp/AbstractAuthorizationDecisionQueryType.php
index da5d778..642dd4f 100644
--- a/src/SAML11/XML/samlp/AbstractAuthorizationDecisionQueryType.php
+++ b/src/SAML11/XML/samlp/AbstractAuthorizationDecisionQueryType.php
@@ -6,11 +6,11 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\saml\Action;
-use SimpleSAML\SAML11\XML\saml\Evidence;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{Action, Evidence, Subject};
+use SimpleSAML\XML\Exception\{MissingElementException, SchemaViolationException};
+
+use function strval;
 
 /**
  * Abstract class to be implemented by all the authorization decision queries in this namespace
@@ -23,17 +23,16 @@ abstract class AbstractAuthorizationDecisionQueryType extends AbstractSubjectQue
      * Initialize a samlp:AuthorizationDecisionQuery element.
      *
      * @param \SimpleSAML\SAML11\XML\saml\Subject $subject
-     * @param string $resource
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue $resource
      * @param \SimpleSAML\SAML11\XML\saml\Evidence|null $evidence
      * @param array<\SimpleSAML\SAML11\XML\saml\Action> $action
      */
     public function __construct(
         Subject $subject,
-        protected string $resource,
+        protected AnyURIValue $resource,
         protected ?Evidence $evidence = null,
         protected array $action = [],
     ) {
-        Assert::validURI($resource, SchemaViolationException::class);
         Assert::allIsInstanceOf($action, Action::class, SchemaViolationException::class);
         Assert::minCount($action, 1, MissingElementException::class);
 
@@ -42,9 +41,9 @@ public function __construct(
 
 
     /**
-     * @return string
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue
      */
-    public function getResource(): string
+    public function getResource(): AnyURIValue
     {
         return $this->resource;
     }
@@ -77,7 +76,7 @@ public function getAction(): array
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toXML($parent);
-        $e->setAttribute('Resource', $this->getResource());
+        $e->setAttribute('Resource', strval($this->getResource()));
 
         foreach ($this->getAction() as $action) {
             $action->toXML($e);
diff --git a/src/SAML11/XML/samlp/AbstractMessage.php b/src/SAML11/XML/samlp/AbstractMessage.php
index b76234c..d8850bb 100644
--- a/src/SAML11/XML/samlp/AbstractMessage.php
+++ b/src/SAML11/XML/samlp/AbstractMessage.php
@@ -4,16 +4,12 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
 use SimpleSAML\SAML11\Utils;
-use SimpleSAML\SAML11\XML\SignableElementTrait;
-use SimpleSAML\SAML11\XML\SignedElementTrait;
-use SimpleSAML\XMLSecurity\XML\SignableElementInterface;
-use SimpleSAML\XMLSecurity\XML\SignedElementInterface;
+use SimpleSAML\SAML11\Type\DateTimeValue;
+use SimpleSAML\SAML11\XML\{SignableElementTrait, SignedElementTrait};
+use SimpleSAML\XML\Type\NonNegativeIntegerValue;
+use SimpleSAML\XMLSecurity\XML\{SignableElementInterface, SignedElementInterface};
 
 use function strval;
 
@@ -32,7 +28,6 @@ abstract class AbstractMessage extends AbstractSamlpElement implements SignableE
         SignedElementTrait::getBlacklistedAlgorithms insteadof SignableElementTrait;
     }
 
-
     /** @var bool */
     protected bool $messageContainedSignatureUponConstruction = false;
 
@@ -47,27 +42,26 @@ abstract class AbstractMessage extends AbstractSamlpElement implements SignableE
     /**
      * Initialize a message.
      *
-     * @param int $majorVersion
-     * @param int $minorVersion
-     * @param \DateTimeImmutable $issueInstant
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $majorVersion
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $minorVersion
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue $issueInstant
      *
      * @throws \Exception
      */
     protected function __construct(
-        protected int $majorVersion,
-        protected int $minorVersion,
-        protected ?DateTimeImmutable $issueInstant,
+        protected NonNegativeIntegerValue $majorVersion,
+        protected NonNegativeIntegerValue $minorVersion,
+        protected ?DateTimeValue $issueInstant,
     ) {
-        Assert::nullOrSame($issueInstant?->getTimeZone()->getName(), 'Z', ProtocolViolationException::class);
     }
 
 
     /**
      * Retrieve the major version of this message.
      *
-     * @return int The major version of this message
+     * @return \SimpleSAML\XML\Type\NonNegativeIntegerValue The major version of this message
      */
-    public function getMajorVersion(): int
+    public function getMajorVersion(): NonNegativeIntegerValue
     {
         return $this->majorVersion;
     }
@@ -76,9 +70,9 @@ public function getMajorVersion(): int
     /**
      * Retrieve the minor version of this message.
      *
-     * @return int The minor version of this message
+     * @return \SimpleSAML\XML\Type\NonNegativeIntegerValue The minor version of this message
      */
-    public function getMinorVersion(): int
+    public function getMinorVersion(): NonNegativeIntegerValue
     {
         return $this->minorVersion;
     }
@@ -87,12 +81,12 @@ public function getMinorVersion(): int
     /**
      * Retrieve the issue timestamp of this message.
      *
-     * @return \DateTimeImmutable The issue timestamp of this message, as an UNIX timestamp
+     * @return \SimpleSAML\SAML11\Type\DateTimeValue The issue timestamp of this message
      */
-    public function getIssueInstant(): DateTimeImmutable
+    public function getIssueInstant(): DateTimeValue
     {
         if ($this->issueInstant === null) {
-            return Utils::getContainer()->getClock()->now();
+            return DateTimeValue::fromDateTime(Utils::getContainer()->getClock()->now());
         }
 
         return $this->issueInstant;
@@ -151,13 +145,9 @@ protected function toUnsignedXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
 
-        /* Ugly hack to add another namespace declaration to the root element. */
-        $e->setAttributeNS(C::NS_SAML, 'saml:tmp', 'tmp');
-        $e->removeAttributeNS(C::NS_SAML, 'tmp');
-
         $e->setAttribute('MajorVersion', strval($this->getMajorVersion()));
         $e->setAttribute('MinorVersion', strval($this->getMinorVersion()));
-        $e->setAttribute('IssueInstant', $this->getIssueInstant()->format(C::DATETIME_FORMAT));
+        $e->setAttribute('IssueInstant', strval($this->getIssueInstant()));
 
         return $e;
     }
diff --git a/src/SAML11/XML/samlp/AbstractQuery.php b/src/SAML11/XML/samlp/AbstractQuery.php
index a25cf2f..26e24e0 100644
--- a/src/SAML11/XML/samlp/AbstractQuery.php
+++ b/src/SAML11/XML/samlp/AbstractQuery.php
@@ -8,17 +8,12 @@
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\Utils;
-use SimpleSAML\SAML11\XML\ExtensionPointInterface;
-use SimpleSAML\SAML11\XML\ExtensionPointTrait;
+use SimpleSAML\SAML11\XML\{ExtensionPointInterface, ExtensionPointTrait};
 use SimpleSAML\XML\Attribute as XMLAttribute;
 use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
-
-use function count;
-use function explode;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, SchemaViolationException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * SAMLP Query data type.
@@ -39,10 +34,10 @@ abstract class AbstractQuery extends AbstractQueryAbstractType implements
     /**
      * Initialize a custom samlp:Query element.
      *
-     * @param string $type
+     * @param \SimpleSAML\XML\Type\QNameValue $type
      */
     protected function __construct(
-        protected string $type,
+        protected QNameValue $type,
     ) {
     }
 
@@ -66,19 +61,7 @@ public static function fromXML(DOMElement $xml): static
             SchemaViolationException::class,
         );
 
-        $type = $xml->getAttributeNS(C::NS_XSI, 'type');
-        Assert::validQName($type, SchemaViolationException::class);
-
-        // first, try to resolve the type to a full namespaced version
-        $qname = explode(':', $type, 2);
-        if (count($qname) === 2) {
-            list($prefix, $element) = $qname;
-        } else {
-            $prefix = null;
-            list($element) = $qname;
-        }
-        $ns = $xml->lookupNamespaceUri($prefix);
-        $type = ($ns === null) ? $element : implode(':', [$ns, $element]);
+        $type = QNameValue::fromDocument($xml->getAttributeNS(C::NS_XSI, 'type'), $xml);
 
         // now check if we have a handler registered for it
         $handler = Utils::getContainer()->getExtensionHandler($type);
@@ -105,11 +88,14 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
-        $e->setAttributeNS(
-            'http://www.w3.org/2000/xmlns/',
-            'xmlns:' . static::getXsiTypePrefix(),
-            static::getXsiTypeNamespaceURI(),
-        );
+
+        if (!$e->lookupPrefix($this->getXsiType()->getNamespaceURI()->getValue())) {
+            $e->setAttributeNS(
+                'http://www.w3.org/2000/xmlns/',
+                'xmlns:' . static::getXsiTypePrefix()->getValue(),
+                static::getXsiTypeNamespaceURI()->getValue(),
+            );
+        }
 
         $type = new XMLAttribute(C::NS_XSI, 'xsi', 'type', $this->getXsiType());
         $type->toXML($e);
diff --git a/src/SAML11/XML/samlp/AbstractRequestAbstractType.php b/src/SAML11/XML/samlp/AbstractRequestAbstractType.php
index f8b3971..f17a0af 100644
--- a/src/SAML11/XML/samlp/AbstractRequestAbstractType.php
+++ b/src/SAML11/XML/samlp/AbstractRequestAbstractType.php
@@ -4,13 +4,15 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\SAML11\Type\DateTimeValue;
 use SimpleSAML\SAML11\Utils\XPath;
 use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Type\{IDValue, NonNegativeIntegerValue};
 
 use function array_pop;
+use function strval;
 
 /**
  * Base class for all SAML 1.1 requests.
@@ -22,22 +24,21 @@ abstract class AbstractRequestAbstractType extends AbstractMessage
     /**
      * Initialize a request.
      *
-     * @param string $id
-     * @param int $majorVersion
-     * @param int $minorVersion
-     * @param \DateTimeImmutable $issueInstant
+     * @param \SimpleSAML\XML\Type\IDValue $id
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $majorVersion
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $minorVersion
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue $issueInstant
      * @param array<\SimpleSAML\SAML11\XML\samlp\RespondWith>
      *
      * @throws \Exception
      */
     protected function __construct(
-        protected string $id,
-        int $majorVersion,
-        int $minorVersion,
-        DateTimeImmutable $issueInstant,
+        protected IDValue $id,
+        protected NonNegativeIntegerValue $majorVersion,
+        protected NonNegativeIntegerValue $minorVersion,
+        protected ?DateTimeValue $issueInstant,
         protected array $respondWith = [],
     ) {
-        Assert::validNCName($id, SchemaViolationException::class);
         Assert::allIsInstanceOf($respondWith, RespondWith::class, SchemaViolationException::class);
 
         parent::__construct($majorVersion, $minorVersion, $issueInstant);
@@ -47,9 +48,9 @@ protected function __construct(
     /**
      * Retrieve the ID of this request.
      *
-     * @return string The ID of this request
+     * @return \SimpleSAML\XML\Type\IDValue The ID of this request
      */
-    public function getID(): string
+    public function getID(): IDValue
     {
         return $this->id;
     }
@@ -73,7 +74,7 @@ public function getRespondWith(): array
     protected function toUnsignedXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toUnsignedXML($parent);
-        $e->setAttribute('RequestID', $this->getID());
+        $e->setAttribute('RequestID', strval($this->getID()));
 
         foreach ($this->getRespondWith() as $respondWith) {
             $respondWith->toXML($e);
diff --git a/src/SAML11/XML/samlp/AbstractRequestType.php b/src/SAML11/XML/samlp/AbstractRequestType.php
index 83a2960..cba6734 100644
--- a/src/SAML11/XML/samlp/AbstractRequestType.php
+++ b/src/SAML11/XML/samlp/AbstractRequestType.php
@@ -4,11 +4,12 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML11\Type\DateTimeValue;
 use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
 use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Type\{IDValue, NonNegativeIntegerValue};
 
 use function array_pop;
 use function is_array;
@@ -28,20 +29,20 @@ abstract class AbstractRequestType extends AbstractRequestAbstractType
      *   array<\SimpleSAML\SAML11\XML\saml\AssertionIDReference>|
      *   array<\SimpleSAML\SAML11\XML\samlp\AssertionArtifact>
      * ) $request
-     * @param string $id
-     * @param int $majorVersion
-     * @param int $minorVersion
-     * @param \DateTimeImmutable $issueInstant
+     * @param \SimpleSAML\XML\Type\IDValue $id
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $majorVersion
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $minorVersion
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue $issueInstant
      * @param array<\SimpleSAML\SAML11\XML\samlp\RespondWith> $respondWith
      *
      * @throws \Exception
      */
     protected function __construct(
         protected AbstractQueryAbstractType|array $request,
-        string $id,
-        int $majorVersion,
-        int $minorVersion,
-        DateTimeImmutable $issueInstant,
+        IDValue $id,
+        NonNegativeIntegerValue $majorVersion,
+        NonNegativeIntegerValue $minorVersion,
+        DateTimeValue $issueInstant,
         array $respondWith = [],
     ) {
         if (is_array($request)) {
diff --git a/src/SAML11/XML/samlp/AbstractResponseAbstractType.php b/src/SAML11/XML/samlp/AbstractResponseAbstractType.php
index f076249..9092aae 100644
--- a/src/SAML11/XML/samlp/AbstractResponseAbstractType.php
+++ b/src/SAML11/XML/samlp/AbstractResponseAbstractType.php
@@ -4,8 +4,11 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
+use SimpleSAML\XML\Type\{IDValue, NonNegativeIntegerValue};
+use SimpleSAML\SAML11\Type\DateTimeValue;
+
+use function strval;
 
 /**
  * Base class for all SAML 1.1 responses.
@@ -20,18 +23,18 @@ abstract class AbstractResponseAbstractType extends AbstractMessage
     /**
      * Initialize a response.
      *
-     * @param string $id
-     * @param int $majorVersion
-     * @param int $minorVersion
-     * @param \DateTimeImmutable|null $issueInstant
+     * @param \SimpleSAML\XML\Type\IDValue $id
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $majorVersion
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $minorVersion
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue|null $issueInstant
      *
      * @throws \Exception
      */
     protected function __construct(
-        protected string $id,
-        int $majorVersion = 1,
-        int $minorVersion = 1,
-        ?DateTimeImmutable $issueInstant = null,
+        protected IDValue $id,
+        NonNegativeIntegerValue $majorVersion,
+        NonNegativeIntegerValue $minorVersion,
+        ?DateTimeValue $issueInstant = null,
     ) {
         parent::__construct($majorVersion, $minorVersion, $issueInstant);
     }
@@ -40,9 +43,9 @@ protected function __construct(
     /**
      * Retrieve the identifier of this message.
      *
-     * @return string The identifier of this message
+     * @return \SimpleSAML\XML\Type\IDValue The identifier of this message
      */
-    public function getID(): string
+    public function getID(): IDValue
     {
         return $this->id;
     }
@@ -57,7 +60,7 @@ public function getID(): string
     protected function toUnsignedXML(?DOMElement $parent = null): DOMElement
     {
         $e = parent::toUnsignedXML($parent);
-        $e->setAttribute('ResponseID', $this->getId());
+        $e->setAttribute('ResponseID', strval($this->getId()));
 
         return $e;
     }
diff --git a/src/SAML11/XML/samlp/AbstractResponseType.php b/src/SAML11/XML/samlp/AbstractResponseType.php
index 2a63140..a8eb831 100644
--- a/src/SAML11/XML/samlp/AbstractResponseType.php
+++ b/src/SAML11/XML/samlp/AbstractResponseType.php
@@ -4,12 +4,15 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\SAML11\Type\{AnyURIValue, DateTimeValue};
 use SimpleSAML\SAML11\XML\saml\Assertion;
 use SimpleSAML\SAML11\XML\samlp\Status;
 use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\Type\{IDValue, NCNameValue, NonNegativeIntegerValue};
+
+use function strval;
 
 /**
  * Base class for all SAML 1.1 samlp:AbstractResponseAbstractType.
@@ -21,29 +24,27 @@ abstract class AbstractResponseType extends AbstractResponseAbstractType
     /**
      * Initialize a response.
      *
-     * @param string $id
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $majorVersion
+     * @param \SimpleSAML\XML\Type\NonNegativeIntegerValue $minorVersion
+     * @param \SimpleSAML\XML\Type\IDValue $id
      * @param \SimpleSAML\SAML11\XML\samlp\Status $status
      * @param array<\SimpleSAML\SAML11\XML\saml\Assertion> $assertion
-     * @param int $majorVersion
-     * @param int $minorVersion
-     * @param \DateTimeImmutable|null $issueInstant
-     * @param string|null $inResponseTo
-     * @param string|null $recipient
+     * @param \SimpleSAML\SAML11\Type\DateTimeValue|null $issueInstant
+     * @param \SimpleSAML\XML\Type\NCNameValue|null $inResponseTo
+     * @param \SimpleSAML\SAML11\Type\AnyURIValue|null $recipient
      *
      * @throws \Exception
      */
     public function __construct(
-        string $id,
+        NonNegativeIntegerValue $majorVersion,
+        NonNegativeIntegerValue $minorVersion,
+        IDValue $id,
         protected Status $status,
         protected array $assertion = [],
-        int $majorVersion = 1,
-        int $minorVersion = 1,
-        ?DateTimeImmutable $issueInstant = null,
-        protected ?string $inResponseTo = null,
-        protected ?string $recipient = null,
+        ?DateTimeValue $issueInstant = null,
+        protected ?NCNameValue $inResponseTo = null,
+        protected ?AnyURIValue $recipient = null,
     ) {
-        Assert::nullOrValidNCName($inResponseTo, SchemaViolationException::class);
-        Assert::nullOrValidURI($recipient, SchemaViolationException::class);
         Assert::allIsInstanceOf($assertion, Assertion::class, SchemaViolationException::class);
 
         parent::__construct($id, $majorVersion, $minorVersion, $issueInstant);
@@ -53,9 +54,9 @@ public function __construct(
     /**
      * Retrieve the inResponseTo of this message.
      *
-     * @return string|null The inResponseTo of this message
+     * @return \SimpleSAML\XML\Type\NCNameValue|null The inResponseTo of this message
      */
-    public function getInResponseTo(): ?string
+    public function getInResponseTo(): ?NCNameValue
     {
         return $this->inResponseTo;
     }
@@ -64,9 +65,9 @@ public function getInResponseTo(): ?string
     /**
      * Retrieve the recipient of this message.
      *
-     * @return string|null The recipient of this message
+     * @return \SimpleSAML\SAML11\Type\AnyURIValue|null The recipient of this message
      */
-    public function getRecipient(): ?string
+    public function getRecipient(): ?AnyURIValue
     {
         return $this->recipient;
     }
@@ -105,11 +106,11 @@ protected function toUnsignedXML(?DOMElement $parent = null): DOMElement
         $e = parent::toUnsignedXML($parent);
 
         if ($this->getRecipient() !== null) {
-            $e->setAttribute('Recipient', $this->getRecipient());
+            $e->setAttribute('Recipient', strval($this->getRecipient()));
         }
 
         if ($this->getInResponseTo() !== null) {
-            $e->setAttribute('InResponseTo', $this->getInResponseTo());
+            $e->setAttribute('InResponseTo', strval($this->getInResponseTo()));
         }
 
         $this->getStatus()->toXML($e);
diff --git a/src/SAML11/XML/samlp/AbstractStatusCodeType.php b/src/SAML11/XML/samlp/AbstractStatusCodeType.php
index ec3a6a4..e4fdce2 100644
--- a/src/SAML11/XML/samlp/AbstractStatusCodeType.php
+++ b/src/SAML11/XML/samlp/AbstractStatusCodeType.php
@@ -8,6 +8,9 @@
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\XML\Type\QNameValue;
+
+use function strval;
 
 /**
  * SAML StatusCode data type.
@@ -19,14 +22,14 @@ abstract class AbstractStatusCodeType extends AbstractSamlpElement
     /**
      * Initialize a samlp:StatusCode
      *
-     * @param string $Value
+     * @param \SimpleSAML\XML\Type\QNameValue $Value
      * @param \SimpleSAML\SAML11\XML\samlp\StatusCode[] $subCodes
      */
     final public function __construct(
-        protected string $Value = C::STATUS_SUCCESS,
+        protected QNameValue $Value,
         protected array $subCodes = [],
     ) {
-        Assert::validQName($Value);
+        Assert::notNull($Value->getNamespacePrefix(), "A namespace prefix MUST be provided.");
         Assert::maxCount($subCodes, C::UNBOUNDED_LIMIT);
         Assert::allIsInstanceOf($subCodes, StatusCode::class);
     }
@@ -35,9 +38,9 @@ final public function __construct(
     /**
      * Collect the Value
      *
-     * @return string
+     * @return \SimpleSAML\XML\Type\QNameValue
      */
-    public function getValue(): string
+    public function getValue(): QNameValue
     {
         return $this->Value;
     }
@@ -70,7 +73,7 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, 'StatusCode', InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, StatusCode::NS, InvalidDOMElementException::class);
 
-        $Value = self::getAttribute($xml, 'Value');
+        $Value = self::getAttribute($xml, 'Value', QNameValue::class);
         $subCodes = StatusCode::getChildrenOfClass($xml);
 
         return new static(
@@ -89,7 +92,7 @@ public static function fromXML(DOMElement $xml): static
     public function toXML(?DOMElement $parent = null): DOMElement
     {
         $e = $this->instantiateParentElement($parent);
-        $e->setAttribute('Value', $this->getValue());
+        $e->setAttribute('Value', strval($this->getValue()));
 
         foreach ($this->getSubCodes() as $subCode) {
             $subCode->toXML($e);
diff --git a/src/SAML11/XML/samlp/AbstractStatusType.php b/src/SAML11/XML/samlp/AbstractStatusType.php
index d63b01f..5608113 100644
--- a/src/SAML11/XML/samlp/AbstractStatusType.php
+++ b/src/SAML11/XML/samlp/AbstractStatusType.php
@@ -8,9 +8,7 @@
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
 
 use function array_pop;
 
@@ -34,13 +32,8 @@ final public function __construct(
         protected ?StatusDetail $statusDetail = null,
     ) {
         Assert::oneOf(
-            $statusCode->getValue(),
-            [
-                C::STATUS_SUCCESS,
-                C::STATUS_REQUESTER,
-                C::STATUS_RESPONDER,
-                C::STATUS_VERSION_MISMATCH,
-            ],
+            $statusCode->getValue()->getValue(),
+            C::$STATUS_CODES,
             'Invalid top-level status code:  %s',
             ProtocolViolationException::class,
         );
diff --git a/src/SAML11/XML/samlp/AbstractSubjectQuery.php b/src/SAML11/XML/samlp/AbstractSubjectQuery.php
index 7a34e5d..8baac1e 100644
--- a/src/SAML11/XML/samlp/AbstractSubjectQuery.php
+++ b/src/SAML11/XML/samlp/AbstractSubjectQuery.php
@@ -8,21 +8,19 @@
 use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\Utils;
-use SimpleSAML\SAML11\XML\ExtensionPointInterface;
-use SimpleSAML\SAML11\XML\ExtensionPointTrait;
+use SimpleSAML\SAML11\XML\{ExtensionPointInterface, ExtensionPointTrait};
 use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Attribute as XMLAttribute;
 use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\SchemaViolationException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\Exception\{
+    InvalidDOMElementException,
+    MissingElementException,
+    SchemaViolationException,
+    TooManyElementsException,
+};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\QNameValue;
 
 use function array_pop;
-use function count;
-use function explode;
 
 /**
  * SAMLP Query data type.
@@ -43,10 +41,10 @@ abstract class AbstractSubjectQuery extends AbstractSubjectQueryAbstractType imp
     /**
      * Initialize a custom samlp:SubjectQuery element.
      *
-     * @param string $type
+     * @param \SimpleSAML\XML\Type\QNameValue $type
      */
     protected function __construct(
-        protected string $type,
+        protected QNameValue $type,
         Subject $subject,
     ) {
         parent::__construct($subject);
@@ -72,19 +70,7 @@ public static function fromXML(DOMElement $xml): static
             SchemaViolationException::class,
         );
 
-        $type = $xml->getAttributeNS(C::NS_XSI, 'type');
-        Assert::validQName($type, SchemaViolationException::class);
-
-        // first, try to resolve the type to a full namespaced version
-        $qname = explode(':', $type, 2);
-        if (count($qname) === 2) {
-            list($prefix, $element) = $qname;
-        } else {
-            $prefix = null;
-            list($element) = $qname;
-        }
-        $ns = $xml->lookupNamespaceUri($prefix);
-        $type = ($ns === null) ? $element : implode(':', [$ns, $element]);
+        $type = QNameValue::fromDocument($xml->getAttributeNS(C::NS_XSI, 'type'), $xml);
 
         // now check if we have a handler registered for it
         $handler = Utils::getContainer()->getExtensionHandler($type);
@@ -105,31 +91,4 @@ public static function fromXML(DOMElement $xml): static
 
         return $handler::fromXML($xml);
     }
-
-
-    /**
-     * Convert this SubjectQuery to XML.
-     *
-     * @param \DOMElement $parent The element we are converting to XML.
-     * @return \DOMElement The XML element after adding the data corresponding to this SubjectQuery.
-     */
-    public function toXML(?DOMElement $parent = null): DOMElement
-    {
-        // This unfortunately doesn't work because namespace attributes get messed up
-        //$e = parent::toXML($parent);
-
-        $e = $this->instantiateParentElement($parent);
-        $e->setAttributeNS(
-            'http://www.w3.org/2000/xmlns/',
-            'xmlns:' . static::getXsiTypePrefix(),
-            static::getXsiTypeNamespaceURI(),
-        );
-
-        $type = new XMLAttribute(C::NS_XSI, 'xsi', 'type', $this->getXsiType());
-        $type->toXML($e);
-
-        $this->getSubject()->toXML($e);
-
-        return $e;
-    }
 }
diff --git a/src/SAML11/XML/samlp/AssertionArtifact.php b/src/SAML11/XML/samlp/AssertionArtifact.php
index 8324102..fac877b 100644
--- a/src/SAML11/XML/samlp/AssertionArtifact.php
+++ b/src/SAML11/XML/samlp/AssertionArtifact.php
@@ -4,9 +4,9 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use SimpleSAML\SAML11\XML\StringElementTrait;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\TypedTextContentTrait;
 
 /**
  * SAML AssertionArtifact element.
@@ -17,17 +17,8 @@
 final class AssertionArtifact extends AbstractSamlpElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use TypedTextContentTrait;
 
-
-    /**
-     * Initialize a saml:AssertionArtifact from scratch
-     *
-     * @param string $value
-     */
-    public function __construct(
-        protected string $value,
-    ) {
-        $this->setContent($value);
-    }
+    /** @var string */
+    public const TEXTCONTENT_TYPE = StringValue::class;
 }
diff --git a/src/SAML11/XML/samlp/AttributeQuery.php b/src/SAML11/XML/samlp/AttributeQuery.php
index 0391214..1264585 100644
--- a/src/SAML11/XML/samlp/AttributeQuery.php
+++ b/src/SAML11/XML/samlp/AttributeQuery.php
@@ -6,13 +6,10 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\saml\AttributeDesignator;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{AttributeDesignator, Subject};
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 use function array_pop;
 
@@ -39,7 +36,7 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, 'AttributeQuery', InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, AttributeQuery::NS, InvalidDOMElementException::class);
 
-        $resource = self::getOptionalAttribute($xml, 'Resource', null);
+        $resource = self::getOptionalAttribute($xml, 'Resource', AnyURIValue::class, null);
 
         $subject = Subject::getChildrenOfClass($xml);
         Assert::minCount($subject, 1, MissingElementException::class);
diff --git a/src/SAML11/XML/samlp/AuthenticationQuery.php b/src/SAML11/XML/samlp/AuthenticationQuery.php
index c34fcc9..1ac169c 100644
--- a/src/SAML11/XML/samlp/AuthenticationQuery.php
+++ b/src/SAML11/XML/samlp/AuthenticationQuery.php
@@ -6,12 +6,10 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML11\Type\AnyURIValue;
 use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 use function array_pop;
 
@@ -38,7 +36,7 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, 'AuthenticationQuery', InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, AuthenticationQuery::NS, InvalidDOMElementException::class);
 
-        $authenticationMethod = self::getAttribute($xml, 'AuthenticationMethod');
+        $authenticationMethod = self::getAttribute($xml, 'AuthenticationMethod', AnyURIValue::class);
 
         $subject = Subject::getChildrenOfClass($xml);
         Assert::minCount($subject, 1, MissingElementException::class);
diff --git a/src/SAML11/XML/samlp/AuthorizationDecisionQuery.php b/src/SAML11/XML/samlp/AuthorizationDecisionQuery.php
index 8ad45ae..da708fe 100644
--- a/src/SAML11/XML/samlp/AuthorizationDecisionQuery.php
+++ b/src/SAML11/XML/samlp/AuthorizationDecisionQuery.php
@@ -6,14 +6,10 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\saml\Action;
-use SimpleSAML\SAML11\XML\saml\Evidence;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{Action, Evidence, Subject};
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 use function array_pop;
 
@@ -41,7 +37,7 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, 'AuthorizationDecisionQuery', InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, AuthorizationDecisionQuery::NS, InvalidDOMElementException::class);
 
-        $resource = self::getAttribute($xml, 'Resource');
+        $resource = self::getAttribute($xml, 'Resource', AnyURIValue::class);
 
         $subject = Subject::getChildrenOfClass($xml);
         Assert::minCount($subject, 1, MissingElementException::class);
diff --git a/src/SAML11/XML/samlp/Request.php b/src/SAML11/XML/samlp/Request.php
index 723dd1d..e714165 100644
--- a/src/SAML11/XML/samlp/Request.php
+++ b/src/SAML11/XML/samlp/Request.php
@@ -4,25 +4,21 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\Assert\Assert as SAMLAssert;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\SAML11\Exception\VersionMismatchException;
+use SimpleSAML\SAML11\Exception\{ProtocolViolationException, VersionMismatchException};
+use SimpleSAML\SAML11\Type\DateTimeValue;
 use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\Type\{IDValue, NonNegativeIntegerValue};
 
 use function array_merge;
 use function array_pop;
-use function preg_replace;
 
 /**
  * Class representing a samlp:Request element.
  *
- * @package simplesaml/xml-saml11
+ * @package simplesaml/saml11
  */
 final class Request extends AbstractRequestType
 {
@@ -80,22 +76,17 @@ public static function fromXML(DOMElement $xml): static
             MissingElementException::class,
         );
 
-        $majorVersion = self::getIntegerAttribute($xml, 'MajorVersion');
-        Assert::same($majorVersion, 1, VersionMismatchException::class);
+        $majorVersion = self::getAttribute($xml, 'MajorVersion', NonNegativeIntegerValue::class);
+        Assert::same($majorVersion->getValue(), '1', VersionMismatchException::class);
 
-        $minorVersion = self::getIntegerAttribute($xml, 'MinorVersion');
-        Assert::same($minorVersion, 1, VersionMismatchException::class);
+        $minorVersion = self::getAttribute($xml, 'MinorVersion', NonNegativeIntegerValue::class);
+        Assert::same($minorVersion->getValue(), '1', VersionMismatchException::class);
 
-        $issueInstant = self::getAttribute($xml, 'IssueInstant');
-        // Strip sub-seconds - See paragraph 1.3.3 of SAML core specifications
-        $issueInstant = preg_replace('/([.][0-9]+Z)$/', 'Z', $issueInstant, 1);
-
-        SAMLAssert::validDateTime($issueInstant, ProtocolViolationException::class);
-        $issueInstant = new DateTimeImmutable($issueInstant);
+        $issueInstant = self::getAttribute($xml, 'IssueInstant', DateTimeValue::class);
 
         return new static(
             $assertionIdReference ?: $assertionArtifact ?: array_pop($query),
-            self::getAttribute($xml, 'RequestID'),
+            self::getAttribute($xml, 'RequestID', IDValue::class),
             $majorVersion,
             $minorVersion,
             $issueInstant,
diff --git a/src/SAML11/XML/samlp/RespondWith.php b/src/SAML11/XML/samlp/RespondWith.php
index 4772b2c..b8d3b0b 100644
--- a/src/SAML11/XML/samlp/RespondWith.php
+++ b/src/SAML11/XML/samlp/RespondWith.php
@@ -4,27 +4,18 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use SimpleSAML\XML\QNameElementTrait;
+use SimpleSAML\XML\Type\QNameValue;
+use SimpleSAML\XML\TypedTextContentTrait;
 
 /**
  * Class representing a samlp:RespondWith element.
  *
- * @package simplesaml/xml-saml11
+ * @package simplesaml/saml11
  */
 final class RespondWith extends AbstractSamlpElement
 {
-    use QNameElementTrait;
+    use TypedTextContentTrait;
 
-
-    /**
-     * Initialize a samlp:RespondWith
-     *
-     * @param string $qname
-     * @param string|null $namespaceUri
-     */
-    public function __construct(string $qname, ?string $namespaceUri = null)
-    {
-        $this->setContent($qname);
-        $this->setContentNamespaceUri($namespaceUri);
-    }
+    /** @var string */
+    public const TEXTCONTENT_TYPE = QNameValue::class;
 }
diff --git a/src/SAML11/XML/samlp/Response.php b/src/SAML11/XML/samlp/Response.php
index 8a13a12..05f0321 100644
--- a/src/SAML11/XML/samlp/Response.php
+++ b/src/SAML11/XML/samlp/Response.php
@@ -4,26 +4,22 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMElement;
 use SimpleSAML\SAML11\Assert\Assert;
-use SimpleSAML\SAML11\Assert\Assert as SAMLAssert;
-use SimpleSAML\SAML11\Exception\ProtocolViolationException;
-use SimpleSAML\SAML11\Exception\VersionMismatchException;
+use SimpleSAML\SAML11\Exception\{ProtocolViolationException, VersionMismatchException};
+use SimpleSAML\SAML11\Type\{AnyURIValue, DateTimeValue};
 use SimpleSAML\SAML11\XML\saml\Assertion;
 use SimpleSAML\SAML11\XML\samlp\Status;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\Type\{IDValue, NCNameValue, NonNegativeIntegerValue};
 
 use function array_pop;
 
 /**
  * Class representing a samlp:Response element.
  *
- * @package simplesaml/xml-saml11
+ * @package simplesaml/saml11
  */
 final class Response extends AbstractResponseType implements SchemaValidatableElementInterface
 {
@@ -47,32 +43,25 @@ public static function fromXML(DOMElement $xml): static
         Assert::same($xml->localName, 'Response', InvalidDOMElementException::class);
         Assert::same($xml->namespaceURI, Response::NS, InvalidDOMElementException::class);
 
-        $majorVersion = self::getIntegerAttribute($xml, 'MajorVersion');
-        Assert::same($majorVersion, 1, VersionMismatchException::class);
+        $majorVersion = self::getAttribute($xml, 'MajorVersion', NonNegativeIntegerValue::class);
+        Assert::same($majorVersion->getValue(), '1', VersionMismatchException::class);
 
-        $minorVersion = self::getIntegerAttribute($xml, 'MinorVersion');
-        Assert::same($minorVersion, 1, VersionMismatchException::class);
-
-        $issueInstant = self::getAttribute($xml, 'IssueInstant');
-        // Strip sub-seconds - See paragraph 1.3.3 of SAML core specifications
-        $issueInstant = preg_replace('/([.][0-9]+Z)$/', 'Z', $issueInstant, 1);
-
-        SAMLAssert::validDateTime($issueInstant, ProtocolViolationException::class);
-        $issueInstant = new DateTimeImmutable($issueInstant);
+        $minorVersion = self::getAttribute($xml, 'MinorVersion', NonNegativeIntegerValue::class);
+        Assert::same($minorVersion->getValue(), '1', VersionMismatchException::class);
 
         $status = Status::getChildrenOfClass($xml);
         Assert::minCount($status, 1, MissingElementException::class);
         Assert::maxCount($status, 1, TooManyElementsException::class);
 
         return new static(
-            self::getAttribute($xml, 'ResponseID'),
-            array_pop($status),
-            Assertion::getChildrenOfClass($xml),
             $majorVersion,
             $minorVersion,
-            $issueInstant,
-            $inResponseTo = self::getOptionalAttribute($xml, 'InResponseTo', null),
-            $recipient = self::getOptionalAttribute($xml, 'Recipient', null),
+            self::getAttribute($xml, 'ResponseID', IDValue::class),
+            array_pop($status),
+            Assertion::getChildrenOfClass($xml),
+            self::getAttribute($xml, 'IssueInstant', DateTimeValue::class),
+            self::getOptionalAttribute($xml, 'InResponseTo', NCNameValue::class, null),
+            self::getOptionalAttribute($xml, 'Recipient', AnyURIValue::class, null),
         );
     }
 }
diff --git a/src/SAML11/XML/samlp/Status.php b/src/SAML11/XML/samlp/Status.php
index 61310d1..082fcdd 100644
--- a/src/SAML11/XML/samlp/Status.php
+++ b/src/SAML11/XML/samlp/Status.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a samlp:Status element.
diff --git a/src/SAML11/XML/samlp/StatusCode.php b/src/SAML11/XML/samlp/StatusCode.php
index 9571ebe..bf1f094 100644
--- a/src/SAML11/XML/samlp/StatusCode.php
+++ b/src/SAML11/XML/samlp/StatusCode.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:StatusCode element.
diff --git a/src/SAML11/XML/samlp/StatusDetail.php b/src/SAML11/XML/samlp/StatusDetail.php
index 5f3f747..1c8d8f8 100644
--- a/src/SAML11/XML/samlp/StatusDetail.php
+++ b/src/SAML11/XML/samlp/StatusDetail.php
@@ -4,8 +4,7 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
 
 /**
  * Class representing a saml:StatusDetail element.
diff --git a/src/SAML11/XML/samlp/StatusMessage.php b/src/SAML11/XML/samlp/StatusMessage.php
index 92fd633..115ee98 100644
--- a/src/SAML11/XML/samlp/StatusMessage.php
+++ b/src/SAML11/XML/samlp/StatusMessage.php
@@ -4,12 +4,9 @@
 
 namespace SimpleSAML\SAML11\XML\samlp;
 
-use DOMElement;
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML11\XML\StringElementTrait;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\SchemaValidatableElementInterface;
-use SimpleSAML\XML\SchemaValidatableElementTrait;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\XML\{SchemaValidatableElementInterface, SchemaValidatableElementTrait};
+use SimpleSAML\XML\TypedTextContentTrait;
 
 /**
  * Class representing a samlp:StatusMessage element.
@@ -19,45 +16,8 @@
 final class StatusMessage extends AbstractSamlpElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use TypedTextContentTrait;
 
-
-    /**
-     * @param string $content
-     */
-    public function __construct(string $content)
-    {
-        $this->setContent($content);
-    }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notWhitespaceOnly($content);
-    }
-
-
-    /**
-     * Convert XML into an StatusMessage
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'StatusMessage', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, StatusMessage::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
+    /** @var string */
+    public const TEXTCONTENT_TYPE = StringValue::class;
 }
diff --git a/src/SAML11/XML/samlp/UnknownQuery.php b/src/SAML11/XML/samlp/UnknownQuery.php
index 7c6543b..978c77f 100644
--- a/src/SAML11/XML/samlp/UnknownQuery.php
+++ b/src/SAML11/XML/samlp/UnknownQuery.php
@@ -6,6 +6,7 @@
 
 use DOMElement;
 use SimpleSAML\XML\Chunk;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Class for unknown queries.
@@ -16,11 +17,11 @@ final class UnknownQuery extends AbstractQuery
 {
     /**
      * @param \SimpleSAML\XML\Chunk $chunk The whole Query element as a chunk object.
-     * @param string $type The xsi:type of this condition.
+     * @param \SimpleSAML\XML\Type\QNameValue $type The xsi:type of this condition.
      */
     public function __construct(
         protected Chunk $chunk,
-        string $type,
+        QNameValue $type,
     ) {
         parent::__construct($type);
     }
diff --git a/src/SAML11/XML/samlp/UnknownSubjectQuery.php b/src/SAML11/XML/samlp/UnknownSubjectQuery.php
index da74743..480e70e 100644
--- a/src/SAML11/XML/samlp/UnknownSubjectQuery.php
+++ b/src/SAML11/XML/samlp/UnknownSubjectQuery.php
@@ -7,6 +7,7 @@
 use DOMElement;
 use SimpleSAML\SAML11\XML\saml\Subject;
 use SimpleSAML\XML\Chunk;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Class for unknown subject queries.
@@ -17,11 +18,11 @@ final class UnknownSubjectQuery extends AbstractSubjectQuery
 {
     /**
      * @param \SimpleSAML\XML\Chunk $chunk The whole SubjectQuery element as a chunk object.
-     * @param string $type The xsi:type of this condition.
+     * @param \SimpleSAML\XML\Type\QNameValue $type The xsi:type of this condition.
      */
     public function __construct(
         protected Chunk $chunk,
-        string $type,
+        QNameValue $type,
         Subject $subject,
     ) {
         parent::__construct($type, $subject);
diff --git a/tests/resources/xml/saml_AttributeStatement.xml b/tests/resources/xml/saml_AttributeStatement.xml
index b40b796..496e03f 100644
--- a/tests/resources/xml/saml_AttributeStatement.xml
+++ b/tests/resources/xml/saml_AttributeStatement.xml
@@ -15,7 +15,7 @@
       </ds:KeyInfo>
     </saml:SubjectConfirmation>
   </saml:Subject>
-  <saml:Attribute xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion" AttributeName="TheName" AttributeNamespace="https://example.org/">
+  <saml:Attribute AttributeName="TheName" AttributeNamespace="https://example.org/">
     <saml:AttributeValue>FirstValue</saml:AttributeValue>
     <saml:AttributeValue>SecondValue</saml:AttributeValue>
   </saml:Attribute>
diff --git a/tests/resources/xml/saml_Conditions.xml b/tests/resources/xml/saml_Conditions.xml
index 0cabf27..9273616 100644
--- a/tests/resources/xml/saml_Conditions.xml
+++ b/tests/resources/xml/saml_Conditions.xml
@@ -2,8 +2,8 @@
   <saml:AudienceRestrictionCondition>
     <saml:Audience>urn:x-simplesamlphp:audience</saml:Audience>
   </saml:AudienceRestrictionCondition>
-  <saml:DoNotCacheCondition xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion" />
-  <saml:Condition xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion" xmlns:ssp="urn:x-simplesamlphp:namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ssp:CustomConditionType">
+  <saml:DoNotCacheCondition />
+  <saml:Condition xmlns:ssp="urn:x-simplesamlphp:namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ssp:CustomConditionType">
     <saml:Audience>urn:some:audience</saml:Audience>
   </saml:Condition>
 </saml:Conditions>
diff --git a/tests/resources/xml/saml_Evidence.xml b/tests/resources/xml/saml_Evidence.xml
index 3f07584..9487c08 100644
--- a/tests/resources/xml/saml_Evidence.xml
+++ b/tests/resources/xml/saml_Evidence.xml
@@ -1,5 +1,5 @@
 <saml:Evidence xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion">
-  <saml:AssertionIDReference xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion">_Test</saml:AssertionIDReference>
+  <saml:AssertionIDReference>_Test</saml:AssertionIDReference>
   <saml:Assertion MajorVersion="1" MinorVersion="1" AssertionID="EvidenceAssertionID" Issuer="urn:x-simplesamlphp:phpunit" IssueInstant="2023-01-24T09:42:26Z">
     <saml:Conditions NotBefore="2023-01-24T09:42:26Z" NotOnOrAfter="2023-01-24T09:47:26Z">
       <saml:AudienceRestrictionCondition>
diff --git a/tests/resources/xml/samlp_AuthorizationDecisionQuery.xml b/tests/resources/xml/samlp_AuthorizationDecisionQuery.xml
index 98e546a..6020d01 100644
--- a/tests/resources/xml/samlp_AuthorizationDecisionQuery.xml
+++ b/tests/resources/xml/samlp_AuthorizationDecisionQuery.xml
@@ -43,7 +43,7 @@
           </saml:SubjectConfirmation>
         </saml:Subject>
         <saml:SubjectLocality IPAddress="127.0.0.1" DNSAddress="simplesamlphp.org" />
-        <saml:AuthorityBinding xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" AuthorityKind="samlp:AttributeQuery" Location="urn:x-simplesamlphp:location" Binding="urn:x-simplesamlphp:binding" />
+        <saml:AuthorityBinding AuthorityKind="samlp:AttributeQuery" Location="urn:x-simplesamlphp:location" Binding="urn:x-simplesamlphp:binding" />
       </saml:AuthenticationStatement>
       <saml:AttributeStatement>
         <saml:Subject>
diff --git a/tests/resources/xml/samlp_Response.xml b/tests/resources/xml/samlp_Response.xml
index b85aa04..645c662 100644
--- a/tests/resources/xml/samlp_Response.xml
+++ b/tests/resources/xml/samlp_Response.xml
@@ -1,4 +1,4 @@
-<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:1.0:assertion" MajorVersion="1" MinorVersion="1" IssueInstant="2023-01-24T09:42:26Z" ResponseID="def456">
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" MajorVersion="1" MinorVersion="1" IssueInstant="2023-01-24T09:42:26Z" ResponseID="def456">
   <samlp:Status>
     <samlp:StatusCode Value="samlp:Responder">
       <samlp:StatusCode Value="samlp:RequestDenied"/>
@@ -30,7 +30,7 @@
         </saml:SubjectConfirmation>
       </saml:Subject>
       <saml:SubjectLocality IPAddress="127.0.0.1" DNSAddress="simplesamlphp.org" />
-      <saml:AuthorityBinding xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" AuthorityKind="samlp:AttributeQuery" Location="urn:x-simplesamlphp:location" Binding="urn:x-simplesamlphp:binding" />
+      <saml:AuthorityBinding AuthorityKind="samlp:AttributeQuery" Location="urn:x-simplesamlphp:location" Binding="urn:x-simplesamlphp:binding" />
     </saml:AuthenticationStatement>
   </saml:Assertion>
 </samlp:Response>
diff --git a/tests/resources/xml/samlp_SubjectQuery.xml b/tests/resources/xml/samlp_SubjectQuery.xml
index 981016b..5abe1e4 100644
--- a/tests/resources/xml/samlp_SubjectQuery.xml
+++ b/tests/resources/xml/samlp_SubjectQuery.xml
@@ -11,7 +11,7 @@
           <ds:X509Certificate>MIICxDCCAi2gAwIBAgIUZ9QDx+SBFHednUWDFGm9tyVKrgQwDQYJKoZIhvcNAQELBQAwczElMCMGA1UEAwwcc2VsZnNpZ25lZC5zaW1wbGVzYW1scGhwLm9yZzEZMBcGA1UECgwQU2ltcGxlU0FNTHBocCBIUTERMA8GA1UEBwwISG9ub2x1bHUxDzANBgNVBAgMBkhhd2FpaTELMAkGA1UEBhMCVVMwIBcNMjIxMjAzMTAzNTQwWhgPMjEyMjExMDkxMDM1NDBaMHMxJTAjBgNVBAMMHHNlbGZzaWduZWQuc2ltcGxlc2FtbHBocC5vcmcxGTAXBgNVBAoMEFNpbXBsZVNBTUxwaHAgSFExETAPBgNVBAcMCEhvbm9sdWx1MQ8wDQYDVQQIDAZIYXdhaWkxCzAJBgNVBAYTAlVTMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDessdFRVDTMQQW3Na81B1CjJV1tmY3nopoIhZrkbDxLa+pv7jGDRcYreyu1DoQxEs06V2nHLoyOPhqJXSFivqtUwVYhR6NYgbNI6RRSsIJCweH0YOdlHna7gULPcLX0Bfbi4odStaFwG9yzDySwSEPtsKxm5pENPjNVGh+jJ+H/QIDAQABo1MwUTAdBgNVHQ4EFgQUvV75t8EoQo2fVa0E9otdtIGK5X0wHwYDVR0jBBgwFoAUvV75t8EoQo2fVa0E9otdtIGK5X0wDwYDVR0TAQH/BAUwAwEB/zANBgkqhkiG9w0BAQsFAAOBgQANQUeiwPJXkWMXuaDHToEBKcezYGqGEYnGUi9LMjeb+Kln7X8nn5iknlz4k77rWCbSwLPC/WDr0ySYQA+HagaeUaFpoiYFJKS6uFlK1HYWnM3W4PUiGHg1/xeZlMO44wTwybXVo0y9KMhchfB5XNbDdoJcqWYvi6xtmZZNRbxUyw==</ds:X509Certificate>
           <ds:X509SubjectName>/CN=selfsigned.simplesamlphp.org/O=SimpleSAMLphp HQ/L=Honolulu/ST=Hawaii/C=US</ds:X509SubjectName>
         </ds:X509Data>
-        <ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>
+        <ssp:Chunk>some</ssp:Chunk>
       </ds:KeyInfo>
     </saml:SubjectConfirmation>
   </saml:Subject>
diff --git a/tests/src/SAML11/Assert/AnyURITest.php b/tests/src/SAML11/Assert/AnyURITest.php
new file mode 100644
index 0000000..37c6268
--- /dev/null
+++ b/tests/src/SAML11/Assert/AnyURITest.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Test\Assert;
+
+use PHPUnit\Framework\Attributes\{CoversClass, DataProvider};
+use PHPUnit\Framework\TestCase;
+use SimpleSAML\Assert\AssertionFailedException;
+use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+
+/**
+ * Class \SimpleSAML\SAML11\Assert\AnyURITest
+ *
+ * @package simplesamlphp/saml11
+ */
+#[CoversClass(Assert::class)]
+final class AnyURITest extends TestCase
+{
+    /**
+     * @param boolean $shouldPass
+     * @param string $uri
+     */
+    #[DataProvider('provideAnyURI')]
+    public function testValidAnyURI(bool $shouldPass, string $uri): void
+    {
+        try {
+            Assert::validAnyURI($uri);
+            $this->assertTrue($shouldPass);
+        } catch (AssertionFailedException | ProtocolViolationException | SchemaViolationException $e) {
+            $this->assertFalse($shouldPass);
+        } finally {
+        }
+    }
+
+
+    /**
+     * @return array<string, array{0: bool, 1: string}>
+     */
+    public static function provideAnyURI(): array
+    {
+        return [
+            'valid' => [true, 'https://simplesamlphp.org'],
+            'empty' => [false, ''],
+            'whitespace' => [false, ' '],
+        ];
+    }
+}
diff --git a/tests/src/SAML11/Assert/DateTimeTest.php b/tests/src/SAML11/Assert/DateTimeTest.php
index 2963736..16b11a2 100644
--- a/tests/src/SAML11/Assert/DateTimeTest.php
+++ b/tests/src/SAML11/Assert/DateTimeTest.php
@@ -4,11 +4,10 @@
 
 namespace SimpleSAML\SAML11\Test\Assert;
 
-use PHPUnit\Framework\Attributes\CoversClass;
-use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\{CoversClass, DataProvider};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Assert\AssertionFailedException;
-use SimpleSAML\SAML11\Assert\Assert as SAML11Assert;
+use SimpleSAML\SAML11\Assert\Assert;
 use SimpleSAML\SAML11\Exception\ProtocolViolationException;
 use SimpleSAML\XML\Exception\SchemaViolationException;
 
@@ -17,7 +16,7 @@
  *
  * @package simplesamlphp/saml11
  */
-#[CoversClass(SAML11Assert::class)]
+#[CoversClass(Assert::class)]
 final class DateTimeTest extends TestCase
 {
     /**
@@ -28,7 +27,7 @@ final class DateTimeTest extends TestCase
     public function testValidDateTime(bool $shouldPass, string $timestamp): void
     {
         try {
-            SAML11Assert::validDateTime($timestamp);
+            Assert::validDateTime($timestamp);
             $this->assertTrue($shouldPass);
         } catch (AssertionFailedException | ProtocolViolationException | SchemaViolationException $e) {
             $this->assertFalse($shouldPass);
diff --git a/tests/src/SAML11/Assert/StringTest.php b/tests/src/SAML11/Assert/StringTest.php
new file mode 100644
index 0000000..8435228
--- /dev/null
+++ b/tests/src/SAML11/Assert/StringTest.php
@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML11\Test\Assert;
+
+use PHPUnit\Framework\Attributes\{CoversClass, DataProvider};
+use PHPUnit\Framework\TestCase;
+use SimpleSAML\SAML11\Assert\Assert;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+
+/**
+ * Class \SimpleSAML\SAML11\Assert\StringTest
+ *
+ * @package simplesamlphp/saml11
+ */
+#[CoversClass(Assert::class)]
+final class StringTest extends TestCase
+{
+    /**
+     * @param boolean $shouldPass
+     * @param string $str
+     */
+    #[DataProvider('provideString')]
+    public function testValidString(bool $shouldPass, string $str): void
+    {
+        try {
+            Assert::validString($str);
+            $this->assertTrue($shouldPass);
+        } catch (ProtocolViolationException | SchemaViolationException $e) {
+            $this->assertFalse($shouldPass);
+        }
+    }
+
+
+    /**
+     * @return array<string, array{0: bool, 1: string}>
+     */
+    public static function provideString(): array
+    {
+        return [
+            'valid' => [true, 'dear diary'],
+            'empty' => [false, ''],
+            'whitespace' => [false, ' '],
+        ];
+    }
+}
diff --git a/tests/src/SAML11/CustomCondition.php b/tests/src/SAML11/CustomCondition.php
index 5e7e237..df68d05 100644
--- a/tests/src/SAML11/CustomCondition.php
+++ b/tests/src/SAML11/CustomCondition.php
@@ -7,9 +7,9 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractCondition;
-use SimpleSAML\SAML11\XML\saml\Audience;
+use SimpleSAML\SAML11\XML\saml\{AbstractCondition, Audience};
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Example class to demonstrate how Condition can be extended.
@@ -38,7 +38,11 @@ public function __construct(
     ) {
         Assert::allIsInstanceOf($audience, Audience::class);
 
-        parent::__construct(self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME);
+        parent::__construct(
+            QNameValue::fromString(
+                '{' . self::XSI_TYPE_NAMESPACE . '}' . self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME,
+            ),
+        );
     }
 
 
diff --git a/tests/src/SAML11/CustomQuery.php b/tests/src/SAML11/CustomQuery.php
index e9e1e5c..dd41f18 100644
--- a/tests/src/SAML11/CustomQuery.php
+++ b/tests/src/SAML11/CustomQuery.php
@@ -7,9 +7,9 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\samlp\AbstractQuery;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
+use SimpleSAML\SAML11\XML\samlp\{AbstractQuery, StatusMessage};
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Example class to demonstrate how Query can be extended.
@@ -38,7 +38,11 @@ public function __construct(
     ) {
         Assert::allIsInstanceOf($statusMessage, StatusMessage::class);
 
-        parent::__construct(self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME);
+        parent::__construct(
+            QNameValue::fromString(
+                '{' . self::XSI_TYPE_NAMESPACE . '}' . self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME,
+            ),
+        );
     }
 
 
diff --git a/tests/src/SAML11/CustomStatement.php b/tests/src/SAML11/CustomStatement.php
index dd9d3d8..1a0e2f0 100644
--- a/tests/src/SAML11/CustomStatement.php
+++ b/tests/src/SAML11/CustomStatement.php
@@ -7,9 +7,9 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractStatement;
-use SimpleSAML\SAML11\XML\saml\Audience;
+use SimpleSAML\SAML11\XML\saml\{AbstractStatement, Audience};
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Example class to demonstrate how Statement can be extended.
@@ -38,7 +38,11 @@ public function __construct(
     ) {
         Assert::allIsInstanceOf($audience, Audience::class);
 
-        parent::__construct(self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME);
+        parent::__construct(
+            QNameValue::fromString(
+                '{' . self::XSI_TYPE_NAMESPACE . '}' . self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME,
+            ),
+        );
     }
 
 
diff --git a/tests/src/SAML11/CustomSubjectQuery.php b/tests/src/SAML11/CustomSubjectQuery.php
index 71951ef..75d3efc 100644
--- a/tests/src/SAML11/CustomSubjectQuery.php
+++ b/tests/src/SAML11/CustomSubjectQuery.php
@@ -8,11 +8,10 @@
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\samlp\AbstractSubjectQuery;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\SAML11\XML\samlp\{AbstractSubjectQuery, StatusMessage};
+use SimpleSAML\XML\Attribute as XMLAttribute;
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\Type\QNameValue;
 
 use function array_pop;
 
@@ -44,7 +43,12 @@ public function __construct(
     ) {
         Assert::allIsInstanceOf($statusMessage, StatusMessage::class);
 
-        parent::__construct(self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME, $subject);
+        parent::__construct(
+            QNameValue::fromString(
+                '{' . self::XSI_TYPE_NAMESPACE . '}' . self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME,
+            ),
+            $subject,
+        );
     }
 
 
@@ -79,8 +83,8 @@ public static function fromXML(DOMElement $xml): static
             InvalidDOMElementException::class,
         );
 
-        $type = $xml->getAttributeNS(C::NS_XSI, 'type');
-        Assert::same($type, self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME);
+        $type = QNameValue::fromDocument($xml->getAttributeNS(C::NS_XSI, 'type'), $xml);
+        Assert::same($type->getValue(), self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME);
 
         $statusMessage = StatusMessage::getChildrenOfClass($xml);
 
@@ -100,7 +104,24 @@ public static function fromXML(DOMElement $xml): static
      */
     public function toXML(?DOMElement $parent = null): DOMElement
     {
-        $e = parent::toXML($parent);
+        $e = $this->instantiateParentElement($parent);
+
+        if (!$e->lookupPrefix($this->getXsiType()->getNamespaceURI()->getValue())) {
+            $namespace = new XMLAttribute(
+                'http://www.w3.org/2000/xmlns/',
+                'xmlns',
+                $this->getXsiType()->getNamespacePrefix()->getValue(),
+                $this->getXsiType()->getNamespaceURI(),
+            );
+            $namespace->toXML($e);
+        }
+
+        if (!$e->lookupPrefix('xsi')) {
+            $type = new XMLAttribute(C::NS_XSI, 'xsi', 'type', $this->getXsiType());
+            $type->toXML($e);
+        }
+
+        $this->getSubject()->toXML($e);
 
         foreach ($this->getStatusMessage() as $statusMessage) {
             $statusMessage->toXML($e);
diff --git a/tests/src/SAML11/CustomSubjectStatement.php b/tests/src/SAML11/CustomSubjectStatement.php
index ba94b02..5540ce3 100644
--- a/tests/src/SAML11/CustomSubjectStatement.php
+++ b/tests/src/SAML11/CustomSubjectStatement.php
@@ -7,12 +7,9 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectStatement;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\Exception\MissingElementException;
-use SimpleSAML\XML\Exception\TooManyElementsException;
+use SimpleSAML\SAML11\XML\saml\{AbstractSubjectStatement, Audience, Subject};
+use SimpleSAML\XML\Exception\{InvalidDOMElementException, MissingElementException, TooManyElementsException};
+use SimpleSAML\XML\Type\QNameValue;
 
 /**
  * Example class to demonstrate how SubjectStatement can be extended.
@@ -43,7 +40,12 @@ public function __construct(
     ) {
         Assert::allIsInstanceOf($audience, Audience::class);
 
-        parent::__construct(self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME, $subject);
+        parent::__construct(
+            QNameValue::fromString(
+                '{' . self::XSI_TYPE_NAMESPACE . '}' . self::XSI_TYPE_PREFIX . ':' . self::XSI_TYPE_NAME,
+            ),
+            $subject,
+        );
     }
 
 
diff --git a/tests/src/SAML11/Type/AnyURIValueTest.php b/tests/src/SAML11/Type/AnyURIValueTest.php
new file mode 100644
index 0000000..1acdf13
--- /dev/null
+++ b/tests/src/SAML11/Type/AnyURIValueTest.php
@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\Test\SAML11\Type;
+
+use PHPUnit\Framework\Attributes\{CoversClass, DataProvider};
+use PHPUnit\Framework\TestCase;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+
+/**
+ * Class \SimpleSAML\Test\SAML11\Type\AnyURIValueTest
+ *
+ * @package simplesamlphp/saml11
+ */
+#[CoversClass(AnyURIValue::class)]
+final class AnyURIValueTest extends TestCase
+{
+    /**
+     * @param boolean $shouldPass
+     * @param string $uri
+     */
+    #[DataProvider('provideURI')]
+    public function testAnyURI(bool $shouldPass, string $uri): void
+    {
+        try {
+            AnyURIValue::fromString($uri);
+            $this->assertTrue($shouldPass);
+        } catch (ProtocolViolationException | SchemaViolationException $e) {
+            $this->assertFalse($shouldPass);
+        }
+    }
+
+
+    /**
+     * @return array<string, array{0: bool, 1: string}>
+     */
+    public static function provideURI(): array
+    {
+        return [
+            'urn' => [true, 'urn:x-simplesamlphp:phpunit'],
+            'same-doc' => [true, '#_53d830ab1be17291a546c95c7f1cdf8d3d23c959e6'],
+            'url' => [true, 'https://www.simplesamlphp.org'],
+            'diacritical' => [true, 'https://aä.com'],
+            'spn' => [true, 'spn:a4cf592f-a64c-46ff-a788-b260f474525b'],
+            'typos' => [true, 'https//www.uni.l/en/'],
+            'spaces' => [true, 'this is silly'],
+            'empty' => [false, ''],
+            'azure-common' => [true, 'https://sts.windows.net/{tenantid}/'],
+        ];
+    }
+}
diff --git a/tests/src/SAML11/Type/DateTimeValueTest.php b/tests/src/SAML11/Type/DateTimeValueTest.php
new file mode 100644
index 0000000..ede855d
--- /dev/null
+++ b/tests/src/SAML11/Type/DateTimeValueTest.php
@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\Test\SAML11\Type;
+
+use PHPUnit\Framework\Attributes\{CoversClass, DataProvider};
+use PHPUnit\Framework\TestCase;
+use SimpleSAML\Assert\AssertionFailedException;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Type\DateTimeValue;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+
+/**
+ * Class \SimpleSAML\Test\SAML11\Type\DateTimeValueTest
+ *
+ * @package simplesamlphp/saml11
+ */
+#[CoversClass(DateTimeValue::class)]
+final class DateTimeValueTest extends TestCase
+{
+    /**
+     * @param boolean $shouldPass
+     * @param string $dateTime
+     */
+    #[DataProvider('provideDateTime')]
+    public function testDateTime(bool $shouldPass, string $dateTime): void
+    {
+        try {
+            DateTimeValue::fromString($dateTime);
+            $this->assertTrue($shouldPass);
+        } catch (AssertionFailedException | ProtocolViolationException | SchemaViolationException $e) {
+            $this->assertFalse($shouldPass);
+        }
+    }
+
+
+    /**
+     * @return array<string, array{0: bool, 1: string}>
+     */
+    public static function provideDateTime(): array
+    {
+        return [
+            'valid' => [true, '2001-10-26T21:32:52Z'],
+            'invalid with numeric difference' => [false, '2001-10-26T21:32:52+02:00'],
+            'invalid with Zulu' => [false, '2001-10-26T19:32:52'],
+            'invalid with 00:00 difference' => [false, '2001-10-26T19:32:52+00:00'],
+            'valid with negative value' => [true, '-2001-10-26T21:32:52Z'],
+            'valid with subseconds' => [true, '2001-10-26T21:32:52.12679Z'],
+            'valid with more than four digit year' => [true, '-22001-10-26T21:32:52Z'],
+            'valid with sub-seconds' => [true, '2001-10-26T21:32:52.12679Z'],
+            'empty' => [false, ''],
+            'whitespace collapse' => [true, ' 2001-10-26T21:32:52Z '],
+            'missing time' => [false, '2001-10-26'],
+            'missing second' => [false, '2001-10-26T21:32'],
+            'hour out of range' => [false, '2001-10-26T25:32:52+02:00'],
+            'year 0000' => [false, '0000-10-26T25:32:52+02:00'],
+            'prefixed zero' => [false, '02001-10-26T25:32:52+02:00'],
+            'wrong format' => [false, '01-10-26T21:32'],
+        ];
+    }
+}
diff --git a/tests/src/SAML11/Type/StringValueTest.php b/tests/src/SAML11/Type/StringValueTest.php
new file mode 100644
index 0000000..2bc09cf
--- /dev/null
+++ b/tests/src/SAML11/Type/StringValueTest.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\Test\SAML11\Type;
+
+use PHPUnit\Framework\Attributes\{CoversClass, DataProvider};
+use PHPUnit\Framework\TestCase;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+
+/**
+ * Class \SimpleSAML\Test\SAML11\Type\StringValueValueTest
+ *
+ * @package simplesamlphp/saml11
+ */
+#[CoversClass(StringValue::class)]
+final class StringValueTest extends TestCase
+{
+    /**
+     * @param boolean $shouldPass
+     * @param string $stringValue
+     */
+    #[DataProvider('provideString')]
+    public function testString(bool $shouldPass, string $stringValue): void
+    {
+        try {
+            StringValue::fromString($stringValue);
+            $this->assertTrue($shouldPass);
+        } catch (ProtocolViolationException | SchemaViolationException $e) {
+            $this->assertFalse($shouldPass);
+        }
+    }
+
+
+    /**
+     * @return array<string, array{0: bool, 1: string}>
+     */
+    public static function provideString(): array
+    {
+        return [
+            'empty string' => [false, ''],
+            'some thing' => [true, 'Snoopy  '],
+        ];
+    }
+}
diff --git a/tests/src/SAML11/XML/saml/ActionTest.php b/tests/src/SAML11/XML/saml/ActionTest.php
index e2dce88..4287117 100644
--- a/tests/src/SAML11/XML/saml/ActionTest.php
+++ b/tests/src/SAML11/XML/saml/ActionTest.php
@@ -4,14 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractActionType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Action;
+use SimpleSAML\SAML11\XML\saml\{AbstractActionType, AbstractSamlElement, Action};
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -21,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Action::class)]
 #[CoversClass(AbstractActionType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -34,8 +33,6 @@ final class ActionTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = Action::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -52,7 +49,10 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $action = new Action('urn:x-simplesamlphp:action', 'urn:x-simplesamlphp:namespace');
+        $action = new Action(
+            StringValue::fromString('urn:x-simplesamlphp:action'),
+            AnyURIValue::fromString('urn:x-simplesamlphp:namespace'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/saml/AdviceTest.php b/tests/src/SAML11/XML/saml/AdviceTest.php
index e60afe1..aed0643 100644
--- a/tests/src/SAML11/XML/saml/AdviceTest.php
+++ b/tests/src/SAML11/XML/saml/AdviceTest.php
@@ -4,47 +4,59 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractAdviceType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatement;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectStatement;
-use SimpleSAML\SAML11\XML\saml\Advice;
-use SimpleSAML\SAML11\XML\saml\Assertion;
-use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
-use SimpleSAML\SAML11\XML\saml\Attribute;
-use SimpleSAML\SAML11\XML\saml\AttributeStatement;
-use SimpleSAML\SAML11\XML\saml\AttributeValue;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AuthenticationStatement;
-use SimpleSAML\SAML11\XML\saml\AuthorityBinding;
-//use SimpleSAML\SAML11\XML\saml\AuthorizationDecisionStatement;
-use SimpleSAML\SAML11\XML\saml\Conditions;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\saml\SubjectLocality;
-use SimpleSAML\Test\SAML11\CustomCondition;
-use SimpleSAML\Test\SAML11\CustomStatement;
-use SimpleSAML\Test\SAML11\CustomSubjectStatement;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    DateTimeValue as SAMLDateTimeValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAdviceType,
+    AbstractSamlElement,
+    AbstractStatement,
+    AbstractSubjectStatement,
+    Advice,
+    Assertion,
+    AssertionIDReference,
+    Attribute,
+    AttributeStatement,
+    AttributeValue,
+    Audience,
+    AuthenticationStatement,
+    AuthorityBinding,
+    //AuthorizationDecisionStatement,
+    Conditions,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+    SubjectLocality,
+};
+use SimpleSAML\Test\SAML11\{CustomCondition, CustomStatement, CustomSubjectStatement};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{
+    Base64BinaryValue,
+    IDValue,
+    IntegerValue,
+    NCNameValue,
+    NonNegativeIntegerValue,
+    QNameValue,
+    StringValue
+};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -54,6 +66,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Advice::class)]
 #[CoversClass(AbstractAdviceType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -180,79 +193,114 @@ public static function tearDownAfterClass(): void
      */
     public function testMarshalling(): void
     {
-        $assertionIDReference = new AssertionIDReference('_Test');
+        $assertionIDReference = new AssertionIDReference(
+            NCNameValue::fromString('_Test'),
+        );
 
         // Create SubjectStatement
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'AdviceSubjectStatementID',
+            IDValue::fromString('AdviceSubjectStatementID'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
         $subjectStatement = new CustomSubjectStatement($subject, [$audience]);
 
         // Create AuthenticationStatement
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'AdviceAuthenticationStatementID',
+            IDValue::fromString('AdviceAuthenticationStatementID'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
-        $subjectLocality = new SubjectLocality('127.0.0.1', 'simplesamlphp.org');
+        $subjectLocality = new SubjectLocality(
+            SAMLStringValue::fromString('127.0.0.1'),
+            SAMLStringValue::fromString('simplesamlphp.org'),
+        );
         $authorityBinding = new AuthorityBinding(
-            'samlp:AttributeQuery',
-            'urn:x-simplesamlphp:location',
-            'urn:x-simplesamlphp:binding',
+            QNameValue::fromString('{' . C::NS_SAMLP . '}samlp:AttributeQuery'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:location'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:binding'),
         );
 
         $authenticationStatement = new AuthenticationStatement(
             $subject,
-            C::AC_PASSWORD,
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            SAMLAnyURIValue::fromString(C::AC_PASSWORD),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             $subjectLocality,
             [$authorityBinding],
         );
@@ -260,22 +308,35 @@ public function testMarshalling(): void
         // Create AttributeStatement
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'AdviceAttributeStatementID',
+            IDValue::fromString('AdviceAttributeStatementID'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
@@ -283,9 +344,16 @@ public function testMarshalling(): void
         $subject = new Subject($sc, $nameIdentifier);
 
         $attribute = new Attribute(
-            'TheName',
-            'https://example.org/',
-            [new AttributeValue('FirstValue'), new AttributeValue('SecondValue')],
+            SAMLStringValue::fromString('TheName'),
+            SAMLAnyURIValue::fromString('https://example.org/'),
+            [
+                new AttributeValue(
+                    SAMLStringValue::fromString('FirstValue'),
+                ),
+                new AttributeValue(
+                    SAMLStringValue::fromString('SecondValue'),
+                ),
+            ],
         );
 
         $attributeStatement = new AttributeStatement(
@@ -295,9 +363,11 @@ public function testMarshalling(): void
 
         // Create assertion
         $assertion = new Assertion(
-            'AdviceAssertionID',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('AdviceAssertionID'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             Conditions::fromXML(self::$conditions->documentElement),
             null, // null
             [
@@ -316,9 +386,11 @@ public function testMarshalling(): void
         );
 
         $assertion = new Assertion(
-            '_abc123',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('_abc123'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             Conditions::fromXML(self::$conditions->documentElement),
             $advice,
             [
diff --git a/tests/src/SAML11/XML/saml/AssertionIDReferenceTest.php b/tests/src/SAML11/XML/saml/AssertionIDReferenceTest.php
index 32694a1..ee5af39 100644
--- a/tests/src/SAML11/XML/saml/AssertionIDReferenceTest.php
+++ b/tests/src/SAML11/XML/saml/AssertionIDReferenceTest.php
@@ -4,13 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
+use SimpleSAML\SAML11\XML\saml\{AbstractSamlElement, AssertionIDReference};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\IDValue;
 
 use function dirname;
 use function strval;
@@ -20,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AssertionIDReference::class)]
 #[CoversClass(AbstractSamlElement::class)]
 final class AssertionIDReferenceTest extends TestCase
@@ -31,8 +31,6 @@ final class AssertionIDReferenceTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AssertionIDReference::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -45,7 +43,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $assertionIDReference = new AssertionIDReference('_Test');
+        $assertionIDReference = new AssertionIDReference(
+            IDValue::fromString('_Test'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/saml/AssertionTest.php b/tests/src/SAML11/XML/saml/AssertionTest.php
index c39084e..1e6d672 100644
--- a/tests/src/SAML11/XML/saml/AssertionTest.php
+++ b/tests/src/SAML11/XML/saml/AssertionTest.php
@@ -4,39 +4,56 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractAssertionType;
-use SimpleSAML\SAML11\XML\saml\AbstractAttributeStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractAuthenticationStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractAuthorizationDecisionStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectStatement;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectStatementType;
-use SimpleSAML\SAML11\XML\saml\Advice;
-use SimpleSAML\SAML11\XML\saml\Assertion;
-use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
-use SimpleSAML\SAML11\XML\saml\{Attribute, AttributeStatement, AttributeValue};
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AuthenticationStatement;
-use SimpleSAML\SAML11\XML\saml\AuthorityBinding;
-use SimpleSAML\SAML11\XML\saml\AuthorizationDecisionStatement;
-use SimpleSAML\SAML11\XML\saml\Conditions;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\{Subject, SubjectConfirmation, SubjectConfirmationData};
-use SimpleSAML\SAML11\XML\saml\SubjectLocality;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    DateTimeValue as SAMLDateTimeValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAssertionType,
+    AbstractAttributeStatementType,
+    AbstractAuthenticationStatementType,
+    AbstractAuthorizationDecisionStatementType,
+    AbstractSamlElement,
+    AbstractStatement,
+    AbstractStatementType,
+    AbstractSubjectStatement,
+    AbstractSubjectStatementType,
+    Advice,
+    Assertion,
+    AssertionIDReference,
+    Attribute,
+    AttributeStatement,
+    AttributeValue,
+    Audience,
+    AuthenticationStatement,
+    AuthorityBinding,
+    AuthorizationDecisionStatement,
+    Conditions,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+    SubjectLocality,
+};
 use SimpleSAML\Test\SAML11\{CustomCondition, CustomStatement, CustomSubjectStatement};
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
 use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{
+    Base64BinaryValue,
+    IDValue,
+    IntegerValue,
+    NCNameValue,
+    NonNegativeIntegerValue,
+    QNameValue,
+    StringValue,
+};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
 use SimpleSAML\XMLSecurity\XML\ds\{KeyInfo, KeyName};
 use SimpleSAML\XMLSecurity\XML\ds\{X509Certificate, X509CertificateName, X509Data, X509SubjectName};
@@ -49,6 +66,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Assertion::class)]
 #[CoversClass(AbstractAssertionType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -193,9 +211,11 @@ public function testMarshalling(): void
 
         // Create inner assertion
         $assertion = new Assertion(
-            'AdviceAssertionID_2',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('AdviceAssertionID_2'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             Conditions::fromXML(self::$conditions->documentElement),
             null, // advice
             [
@@ -208,7 +228,9 @@ public function testMarshalling(): void
         );
 
         // Create middle assertion
-        $assertionIDReference = new AssertionIDReference('_Test');
+        $assertionIDReference = new AssertionIDReference(
+            NCNameValue::fromString('_Test'),
+        );
         $advice = new Advice(
             [$assertionIDReference],
             [$assertion],
@@ -225,9 +247,11 @@ public function testMarshalling(): void
         $attributeStatement = $this->createAttributeStatement('AdviceAttributeStatementID');
 
         $assertion = new Assertion(
-            'AdviceAssertionID',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('AdviceAssertionID'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             Conditions::fromXML(self::$conditions->documentElement),
             $advice,
             [
@@ -247,9 +271,11 @@ public function testMarshalling(): void
         );
 
         $assertion = new Assertion(
-            'AssertionID',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('AssertionID'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             Conditions::fromXML(self::$conditions->documentElement),
             $advice,
             [
@@ -307,38 +333,56 @@ public function testStatementGetters(): void
     private function createSubjectStatement(string $id): CustomSubjectStatement
     {
         // Create SubjectStatement
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            $id,
+            IDValue::fromString($id),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
+
         return new CustomSubjectStatement($subject, [$audience]);
     }
 
@@ -349,49 +393,68 @@ private function createSubjectStatement(string $id): CustomSubjectStatement
      */
     private function createAuthenticationStatement(string $id): AuthenticationStatement
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            $id,
+            IDValue::fromString($id),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
-        $subjectLocality = new SubjectLocality('127.0.0.1', 'simplesamlphp.org');
+        $subjectLocality = new SubjectLocality(
+            SAMLStringValue::fromString('127.0.0.1'),
+            SAMLStringValue::fromString('simplesamlphp.org'),
+        );
+
         $authorityBinding = new AuthorityBinding(
-            'samlp:AttributeQuery',
-            'urn:x-simplesamlphp:location',
-            'urn:x-simplesamlphp:binding',
+            QNameValue::fromString('{' . C::NS_SAMLP . '}samlp:AttributeQuery'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:location'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:binding'),
         );
 
         return new AuthenticationStatement(
             $subject,
-            C::AC_PASSWORD,
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            SAMLAnyURIValue::fromString(C::AC_PASSWORD),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             $subjectLocality,
             [$authorityBinding],
         );
@@ -404,42 +467,64 @@ private function createAuthenticationStatement(string $id): AuthenticationStatem
      */
     private function createAttributeStatement(string $id): AttributeStatement
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            $id,
+            IDValue::fromString($id),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
         $attribute = new Attribute(
-            'TheName',
-            'https://example.org/',
-            [new AttributeValue('FirstValue'), new AttributeValue('SecondValue')],
+            SAMLStringValue::fromString('TheName'),
+            SAMLAnyURIValue::fromString('https://example.org/'),
+            [
+                new AttributeValue(
+                    SAMLStringValue::fromString('FirstValue'),
+                ),
+                new AttributeValue(
+                    SAMLStringValue::fromString('SecondValue'),
+                ),
+            ],
         );
 
         return new AttributeStatement(
diff --git a/tests/src/SAML11/XML/saml/AttributeDesignatorTest.php b/tests/src/SAML11/XML/saml/AttributeDesignatorTest.php
index 9347049..6b69041 100644
--- a/tests/src/SAML11/XML/saml/AttributeDesignatorTest.php
+++ b/tests/src/SAML11/XML/saml/AttributeDesignatorTest.php
@@ -4,14 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractAttributeDesignatorType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AttributeDesignator;
+use SimpleSAML\SAML11\XML\saml\{AbstractAttributeDesignatorType, AbstractSamlElement, AttributeDesignator};
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -21,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AttributeDesignator::class)]
 #[CoversClass(AbstractAttributeDesignatorType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -34,8 +33,6 @@ final class AttributeDesignatorTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AttributeDesignator::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -52,8 +49,8 @@ public static function setUpBeforeClass(): void
     public function testMarshalling(): void
     {
         $attributeDesignator = new AttributeDesignator(
-            'TheName',
-            'https://example.org/',
+            StringValue::fromString('TheName'),
+            AnyURIValue::fromString('https://example.org/'),
         );
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/saml/AttributeStatementTest.php b/tests/src/SAML11/XML/saml/AttributeStatementTest.php
index 377af2b..33b5f30 100644
--- a/tests/src/SAML11/XML/saml/AttributeStatementTest.php
+++ b/tests/src/SAML11/XML/saml/AttributeStatementTest.php
@@ -4,29 +4,36 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    StringValue as SAMLStringValue,
+};
 use SimpleSAML\SAML11\Utils\XPath;
-use SimpleSAML\SAML11\XML\saml\AbstractAttributeStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Attribute;
-use SimpleSAML\SAML11\XML\saml\AttributeStatement;
-use SimpleSAML\SAML11\XML\saml\AttributeValue;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAttributeStatementType,
+    AbstractSamlElement,
+    Attribute,
+    AttributeStatement,
+    AttributeValue,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, IntegerValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -36,6 +43,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AttributeStatement::class)]
 #[CoversClass(AbstractAttributeStatementType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -55,8 +63,6 @@ final class AttributeStatementTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AttributeStatement::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -97,42 +103,64 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'AttributeStatementID',
+            IDValue::fromString('AttributeStatementID'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
         $attribute = new Attribute(
-            'TheName',
-            'https://example.org/',
-            [new AttributeValue('FirstValue'), new AttributeValue('SecondValue')],
+            SAMLStringValue::fromString('TheName'),
+            SAMLAnyURIValue::fromString('https://example.org/'),
+            [
+                new AttributeValue(
+                    SAMLStringValue::fromString('FirstValue'),
+                ),
+                new AttributeValue(
+                    SAMLStringValue::fromString('SecondValue'),
+                ),
+            ],
         );
 
         $attributeStatement = new AttributeStatement(
diff --git a/tests/src/SAML11/XML/saml/AttributeTest.php b/tests/src/SAML11/XML/saml/AttributeTest.php
index 3e727a0..e1432f6 100644
--- a/tests/src/SAML11/XML/saml/AttributeTest.php
+++ b/tests/src/SAML11/XML/saml/AttributeTest.php
@@ -4,17 +4,19 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractAttributeDesignatorType;
-use SimpleSAML\SAML11\XML\saml\AbstractAttributeType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Attribute;
-use SimpleSAML\SAML11\XML\saml\AttributeValue;
+use SimpleSAML\SAML11\Type\{AnyURIValue, DateTimeValue, StringValue};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAttributeDesignatorType,
+    AbstractAttributeType,
+    AbstractSamlElement,
+    Attribute,
+    AttributeValue,
+};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\IntegerValue;
 
 use function dirname;
 use function strval;
@@ -24,6 +26,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Attribute::class)]
 #[CoversClass(AttributeValue::class)]
 #[CoversClass(AbstractAttributeType::class)]
@@ -39,8 +42,6 @@ final class AttributeTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = Attribute::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -57,13 +58,21 @@ public static function setUpBeforeClass(): void
     public function testMarshalling(): void
     {
         $attribute = new Attribute(
-            'TheName',
-            'https://example.org/',
+            StringValue::fromString('TheName'),
+            AnyURIValue::fromString('https://example.org/'),
             [
-                new AttributeValue('FirstValue'),
-                new AttributeValue('SecondValue'),
-                new AttributeValue(3),
-                new AttributeValue(new DateTimeImmutable('2024-04-04T04:44:44Z')),
+                new AttributeValue(
+                    StringValue::fromString('FirstValue'),
+                ),
+                new AttributeValue(
+                    StringValue::fromString('SecondValue'),
+                ),
+                new AttributeValue(
+                    IntegerValue::fromString('3'),
+                ),
+                new AttributeValue(
+                    DateTimeValue::fromString('2024-04-04T04:44:44Z'),
+                ),
             ],
         );
 
diff --git a/tests/src/SAML11/XML/saml/AttributeValueTest.php b/tests/src/SAML11/XML/saml/AttributeValueTest.php
index 74b1920..4420f52 100644
--- a/tests/src/SAML11/XML/saml/AttributeValueTest.php
+++ b/tests/src/SAML11/XML/saml/AttributeValueTest.php
@@ -4,16 +4,15 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AttributeValue;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Type\{DateTimeValue, StringValue};
+use SimpleSAML\SAML11\XML\saml\{AbstractSamlElement, AttributeValue, NameIdentifier};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\IntegerValue;
 use TypeError;
 
 use function dirname;
@@ -24,6 +23,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AttributeValue::class)]
 #[CoversClass(AbstractSamlElement::class)]
 final class AttributeValueTest extends TestCase
@@ -35,8 +35,6 @@ final class AttributeValueTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AttributeValue::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -53,9 +51,10 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $av = new AttributeValue(2);
-        $this->assertIsInt($av->getValue());
-        $this->assertEquals(2, $av->getValue());
+        $av = new AttributeValue(
+            IntegerValue::fromString('2'),
+        );
+        $this->assertEquals('2', $av->getValue());
         $this->assertEquals('xs:integer', $av->getXsiType());
 
         $this->assertEquals(
@@ -70,7 +69,9 @@ public function testMarshalling(): void
      */
     public function testMarshallingString(): void
     {
-        $av = new AttributeValue('value');
+        $av = new AttributeValue(
+            StringValue::fromString('value'),
+        );
 
         $this->assertEquals('value', $av->getValue());
         $this->assertEquals('xs:string', $av->getXsiType());
@@ -82,9 +83,11 @@ public function testMarshallingString(): void
      */
     public function testMarshallingInteger(): void
     {
-        $av = new AttributeValue(3);
+        $av = new AttributeValue(
+            IntegerValue::fromString('3'),
+        );
 
-        $this->assertEquals(3, $av->getValue());
+        $this->assertEquals('3', strval($av->getValue()));
         $this->assertEquals('xs:integer', $av->getXsiType());
 
         $nssaml = C::NS_SAML;
@@ -105,11 +108,12 @@ public function testMarshallingInteger(): void
      */
     public function testMarshallingDateTime(): void
     {
-        $av = new AttributeValue(new DateTimeImmutable("2024-04-04T04:44:44Z"));
+        $av = new AttributeValue(
+            DateTimeValue::fromString("2024-04-04T04:44:44Z"),
+        );
 
-        /** @var \DateTimeInterface $value */
         $value = $av->getValue();
-        $this->assertEquals('2024-04-04T04:44:44Z', $value->format(C::DATETIME_FORMAT));
+        $this->assertEquals('2024-04-04T04:44:44Z', strval($value));
         $this->assertEquals('xs:dateTime', $av->getXsiType());
 
         $nssaml = C::NS_SAML;
@@ -126,21 +130,12 @@ public function testMarshallingDateTime(): void
 
 
     /**
-     * Verifies that supplying an empty string as attribute value will
-     * generate a tag with no content (instead of e.g. an empty tag).
-     *
+     * Verifies that supplying an empty string as attribute value will throw an exception.
      */
     public function testEmptyStringAttribute(): void
     {
-        $av = new AttributeValue('');
-        $xmlRepresentation = clone self::$xmlRepresentation;
-        $xmlRepresentation->documentElement->textContent = '';
-//        $this->assertEqualXMLStructure(
-//            $this->xmlRepresentation->documentElement,
-//            $av->toXML(),
-//        );
-        $this->assertEquals('', $av->getValue());
-        $this->assertEquals('xs:string', $av->getXsiType());
+        $this->expectException(ProtocolViolationException::class);
+        new AttributeValue(StringValue::fromString(''));
     }
 
 
@@ -163,7 +158,7 @@ public function testUnmarshallingNameID(): void
 
         $this->assertInstanceOf(NameIdentifier::class, $value);
 
-        $this->assertEquals('abcd-some-value-xyz', $value->getContent());
+        $this->assertEquals('abcd-some-value-xyz', $value->getValue());
         $this->assertEquals('urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified', $value->getFormat());
         $this->assertXmlStringEqualsXmlString($document->saveXML(), $av->toXML()->ownerDocument?->saveXML());
     }
diff --git a/tests/src/SAML11/XML/saml/AudienceRestrictionConditionTest.php b/tests/src/SAML11/XML/saml/AudienceRestrictionConditionTest.php
index 1765259..4eb599b 100644
--- a/tests/src/SAML11/XML/saml/AudienceRestrictionConditionTest.php
+++ b/tests/src/SAML11/XML/saml/AudienceRestrictionConditionTest.php
@@ -4,15 +4,17 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractAudienceRestrictionConditionType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AudienceRestrictionCondition;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAudienceRestrictionConditionType,
+    AbstractSamlElement,
+    Audience,
+    AudienceRestrictionCondition,
+};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -22,6 +24,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AudienceRestrictionCondition::class)]
 #[CoversClass(AbstractAudienceRestrictionConditionType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -35,8 +38,6 @@ final class AudienceRestrictionConditionTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AudienceRestrictionCondition::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -53,7 +54,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            AnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
         $audienceRestrictionCondition = new AudienceRestrictionCondition([$audience]);
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/saml/AudienceTest.php b/tests/src/SAML11/XML/saml/AudienceTest.php
index ea83933..38da66f 100644
--- a/tests/src/SAML11/XML/saml/AudienceTest.php
+++ b/tests/src/SAML11/XML/saml/AudienceTest.php
@@ -4,13 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Audience;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{AbstractSamlElement, Audience};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -20,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Audience::class)]
 #[CoversClass(AbstractSamlElement::class)]
 final class AudienceTest extends TestCase
@@ -32,8 +32,6 @@ final class AudienceTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = Audience::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -50,7 +48,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            AnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/saml/AuthenticationStatementTest.php b/tests/src/SAML11/XML/saml/AuthenticationStatementTest.php
index c575aa8..8430443 100644
--- a/tests/src/SAML11/XML/saml/AuthenticationStatementTest.php
+++ b/tests/src/SAML11/XML/saml/AuthenticationStatementTest.php
@@ -4,31 +4,38 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    DateTimeValue as SAMLDateTimeValue,
+    StringValue as SAMLStringValue,
+};
 use SimpleSAML\SAML11\Utils\XPath;
-use SimpleSAML\SAML11\XML\saml\AbstractAuthenticationStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AuthenticationStatement;
-use SimpleSAML\SAML11\XML\saml\AuthorityBinding;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\saml\SubjectLocality;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAuthenticationStatementType,
+    AbstractSamlElement,
+    AuthenticationStatement,
+    AuthorityBinding,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+    SubjectLocality,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, IntegerValue, QNameValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -38,6 +45,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AuthenticationStatement::class)]
 #[CoversClass(AbstractAuthenticationStatementType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -57,8 +65,6 @@ final class AuthenticationStatementTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AuthenticationStatement::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -99,49 +105,68 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'AuthenticationStatementID',
+            IDValue::fromString('AuthenticationStatementID'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
-        $subjectLocality = new SubjectLocality('127.0.0.1', 'simplesamlphp.org');
+        $subjectLocality = new SubjectLocality(
+            SAMLStringValue::fromString('127.0.0.1'),
+            SAMLStringValue::fromString('simplesamlphp.org'),
+        );
+
         $authorityBinding = new AuthorityBinding(
-            'samlp:AttributeQuery',
-            'urn:x-simplesamlphp:location',
-            'urn:x-simplesamlphp:binding',
+            QNameValue::fromString('{' . C::NS_SAMLP . '}samlp:AttributeQuery'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:location'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:binding'),
         );
 
         $authenticationStatement = new AuthenticationStatement(
             $subject,
-            C::AC_PASSWORD,
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            SAMLAnyURIValue::fromString(C::AC_PASSWORD),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             $subjectLocality,
             [$authorityBinding],
         );
diff --git a/tests/src/SAML11/XML/saml/AuthorityBindingTest.php b/tests/src/SAML11/XML/saml/AuthorityBindingTest.php
index deefe12..541fd7e 100644
--- a/tests/src/SAML11/XML/saml/AuthorityBindingTest.php
+++ b/tests/src/SAML11/XML/saml/AuthorityBindingTest.php
@@ -4,14 +4,14 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractAuthorityBindingType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AuthorityBinding;
+use SimpleSAML\SAML11\Constants as C;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{AbstractAuthorityBindingType, AbstractSamlElement, AuthorityBinding};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{NCNameValue, QNameValue};
 
 use function dirname;
 use function strval;
@@ -21,6 +21,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AuthorityBinding::class)]
 #[CoversClass(AbstractAuthorityBindingType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -34,8 +35,6 @@ final class AuthorityBindingTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = AuthorityBinding::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -53,9 +52,13 @@ public static function setUpBeforeClass(): void
     public function testMarshalling(): void
     {
         $ab = new AuthorityBinding(
-            'samlp:AttributeQuery',
-            'urn:x-simplesamlphp:location',
-            'urn:x-simplesamlphp:binding',
+            QNameValue::fromParts(
+                NCNameValue::fromString('AttributeQuery'),
+                AnyURIValue::fromString(C::NS_SAMLP),
+                NCNameValue::fromString('samlp'),
+            ),
+            AnyURIValue::fromString('urn:x-simplesamlphp:location'),
+            AnyURIValue::fromString('urn:x-simplesamlphp:binding'),
         );
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/saml/AuthorizationDecisionStatementTest.php b/tests/src/SAML11/XML/saml/AuthorizationDecisionStatementTest.php
index 268530c..5336d31 100644
--- a/tests/src/SAML11/XML/saml/AuthorizationDecisionStatementTest.php
+++ b/tests/src/SAML11/XML/saml/AuthorizationDecisionStatementTest.php
@@ -5,23 +5,22 @@
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
-use SimpleSAML\SAML11\XML\saml\AbstractAuthorizationDecisionStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Action;
-use SimpleSAML\SAML11\XML\saml\AuthorizationDecisionStatement;
-use SimpleSAML\SAML11\XML\saml\DecisionTypeEnum;
-use SimpleSAML\SAML11\XML\saml\Evidence;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\Test\SAML11\CustomCondition;
-use SimpleSAML\Test\SAML11\CustomStatement;
-use SimpleSAML\Test\SAML11\CustomSubjectStatement;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractAuthorizationDecisionStatementType,
+    AbstractSamlElement,
+    Action,
+    AuthorizationDecisionStatement,
+    DecisionTypeEnum,
+    Evidence,
+    Subject,
+};
+use SimpleSAML\Test\SAML11\{CustomCondition, CustomStatement, CustomSubjectStatement};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -31,6 +30,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AuthorizationDecisionStatement::class)]
 #[CoversClass(AbstractAuthorizationDecisionStatementType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -115,7 +115,7 @@ public function testMarshalling(): void
 
         $authzDecisionStatement = new AuthorizationDecisionStatement(
             $subject,
-            'urn:x-simplesamlphp:resource',
+            AnyURIValue::fromString('urn:x-simplesamlphp:resource'),
             DecisionTypeEnum::Permit,
             [$action],
             $evidence,
diff --git a/tests/src/SAML11/XML/saml/ConditionTest.php b/tests/src/SAML11/XML/saml/ConditionTest.php
index 3996907..bd2f79d 100644
--- a/tests/src/SAML11/XML/saml/ConditionTest.php
+++ b/tests/src/SAML11/XML/saml/ConditionTest.php
@@ -4,20 +4,21 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractCondition;
-use SimpleSAML\SAML11\XML\saml\AbstractConditionType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\UnknownCondition;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractCondition,
+    AbstractConditionType,
+    AbstractSamlElement,
+    Audience,
+    UnknownCondition,
+};
 use SimpleSAML\Test\SAML11\CustomCondition;
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -27,6 +28,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(UnknownCondition::class)]
 #[CoversClass(AbstractCondition::class)]
 #[CoversClass(AbstractConditionType::class)]
@@ -77,7 +79,11 @@ public static function tearDownAfterClass(): void
     public function testMarshalling(): void
     {
         $condition = new CustomCondition(
-            [new Audience('urn:some:audience')],
+            [
+                new Audience(
+                    AnyURIValue::fromString('urn:some:audience'),
+                ),
+            ],
         );
 
         $this->assertEquals(
@@ -100,7 +106,10 @@ public function testUnmarshallingUnregistered(): void
         $condition = AbstractCondition::fromXML($element);
 
         $this->assertInstanceOf(UnknownCondition::class, $condition);
-        $this->assertEquals('urn:x-simplesamlphp:namespace:UnknownConditionType', $condition->getXsiType());
+        $this->assertEquals(
+            '{urn:x-simplesamlphp:namespace}ssp:UnknownConditionType',
+            $condition->getXsiType()->getRawValue(),
+        );
 
         $chunk = $condition->getRawCondition();
         $this->assertEquals('saml', $chunk->getPrefix());
diff --git a/tests/src/SAML11/XML/saml/ConditionsTest.php b/tests/src/SAML11/XML/saml/ConditionsTest.php
index 57a9bc4..91ede79 100644
--- a/tests/src/SAML11/XML/saml/ConditionsTest.php
+++ b/tests/src/SAML11/XML/saml/ConditionsTest.php
@@ -4,20 +4,21 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractConditionsType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AudienceRestrictionCondition;
-use SimpleSAML\SAML11\XML\saml\Conditions;
-use SimpleSAML\SAML11\XML\saml\DoNotCacheCondition;
+use SimpleSAML\SAML11\Type\{AnyURIValue, DateTimeValue};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractConditionsType,
+    AbstractSamlElement,
+    Audience,
+    AudienceRestrictionCondition,
+    Conditions,
+    DoNotCacheCondition,
+};
 use SimpleSAML\Test\SAML11\CustomCondition;
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -27,6 +28,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Conditions::class)]
 #[CoversClass(AbstractConditionsType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -58,21 +60,27 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            AnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
         $audienceRestrictionCondition = new AudienceRestrictionCondition([$audience]);
 
         $doNotCacheCondition = new DoNotCacheCondition();
 
         $condition = new CustomCondition(
-            [new Audience('urn:some:audience')],
+            [
+                new Audience(
+                    AnyURIValue::fromString('urn:some:audience'),
+                ),
+            ],
         );
 
         $conditions = new Conditions(
             [$audienceRestrictionCondition],
             [$doNotCacheCondition],
             [$condition],
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
-            new DateTimeImmutable('2023-01-24T09:47:26Z'),
+            DateTimeValue::fromString('2023-01-24T09:42:26Z'),
+            DateTimeValue::fromString('2023-01-24T09:47:26Z'),
         );
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/saml/ConfirmationMethodTest.php b/tests/src/SAML11/XML/saml/ConfirmationMethodTest.php
index 842c29b..81317f1 100644
--- a/tests/src/SAML11/XML/saml/ConfirmationMethodTest.php
+++ b/tests/src/SAML11/XML/saml/ConfirmationMethodTest.php
@@ -4,13 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{AbstractSamlElement, ConfirmationMethod};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -20,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(ConfirmationMethod::class)]
 #[CoversClass(AbstractSamlElement::class)]
 final class ConfirmationMethodTest extends TestCase
@@ -31,8 +31,6 @@ final class ConfirmationMethodTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = ConfirmationMethod::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -45,7 +43,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $confirmationMethod = new ConfirmationMethod('_Test');
+        $confirmationMethod = new ConfirmationMethod(
+            AnyURIValue::fromString('_Test'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/saml/DoNotCacheConditionTest.php b/tests/src/SAML11/XML/saml/DoNotCacheConditionTest.php
index 1982e2c..255ee58 100644
--- a/tests/src/SAML11/XML/saml/DoNotCacheConditionTest.php
+++ b/tests/src/SAML11/XML/saml/DoNotCacheConditionTest.php
@@ -4,14 +4,15 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractDoNotCacheConditionType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\DoNotCacheCondition;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractDoNotCacheConditionType,
+    AbstractSamlElement,
+    DoNotCacheCondition,
+};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -21,6 +22,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(DoNotCacheCondition::class)]
 #[CoversClass(AbstractDoNotCacheConditionType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -34,8 +36,6 @@ final class DoNotCacheConditionTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = DoNotCacheCondition::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
diff --git a/tests/src/SAML11/XML/saml/EvidenceTest.php b/tests/src/SAML11/XML/saml/EvidenceTest.php
index b1db10a..f4ea136 100644
--- a/tests/src/SAML11/XML/saml/EvidenceTest.php
+++ b/tests/src/SAML11/XML/saml/EvidenceTest.php
@@ -4,36 +4,57 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use DateTimeImmutable;
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractEvidenceType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatement;
-//use SimpleSAML\SAML11\XML\saml\Advice;
-use SimpleSAML\SAML11\XML\saml\Assertion;
-use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
-use SimpleSAML\SAML11\XML\saml\{Attribute, AttributeStatement, AttributeValue};
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AuthenticationStatement;
-//use SimpleSAML\SAML11\XML\saml\AuthorizationDecisionStatement;
-use SimpleSAML\SAML11\XML\saml\AuthorityBinding;
-use SimpleSAML\SAML11\XML\saml\Conditions;
-use SimpleSAML\SAML11\XML\saml\Evidence;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    DateTimeValue as SAMLDateTimeValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractEvidenceType,
+    AbstractSamlElement,
+    AbstractStatement,
+    //Advice,
+    Assertion,
+    AssertionIDReference,
+    Attribute,
+    AttributeStatement,
+    AttributeValue,
+    Audience,
+    AuthenticationStatement,
+    //AuthorizationDecisionStatement,
+    AuthorityBinding,
+    Conditions,
+    ConfirmationMethod,
+    Evidence,
+    NameIdentifier,
+};
 use SimpleSAML\SAML11\XML\saml\{Subject, SubjectConfirmation, SubjectConfirmationData, SubjectLocality};
 use SimpleSAML\Test\SAML11\{CustomCondition, CustomStatement, CustomSubjectStatement};
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
 use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{
+    Base64BinaryValue,
+    IDValue,
+    IntegerValue,
+    NCNameValue,
+    NonNegativeIntegerValue,
+    QNameValue,
+    StringValue,
+};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\{KeyInfo, KeyName};
-use SimpleSAML\XMLSecurity\XML\ds\{X509Certificate, X509CertificateName, X509Data, X509SubjectName};
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509CertificateName,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -43,6 +64,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Evidence::class)]
 #[CoversClass(AbstractEvidenceType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -161,12 +183,16 @@ public function testMarshalling(): void
         // Create AttributeStatement
         $attributeStatement = $this->createAttributeStatement('EvidenceAttributeStatementID');
 
-        $assertionIDReference = new AssertionIDReference('_Test');
+        $assertionIDReference = new AssertionIDReference(
+            NCNameValue::fromString('_Test'),
+        );
 
         $assertion = new Assertion(
-            'EvidenceAssertionID',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('EvidenceAssertionID'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             Conditions::fromXML(self::$conditions->documentElement),
             null, // advice
             [
@@ -194,38 +220,57 @@ public function testMarshalling(): void
     private function createSubjectStatement(string $id): CustomSubjectStatement
     {
         // Create SubjectStatement
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            $id,
+            IDValue::fromString($id),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+
+        $audience = new Audience(
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
+
         return new CustomSubjectStatement($subject, [$audience]);
     }
 
@@ -236,49 +281,69 @@ private function createSubjectStatement(string $id): CustomSubjectStatement
      */
     private function createAuthenticationStatement(string $id): AuthenticationStatement
     {
-        $scd = new SubjectConfirmationData(2);
+        // Create AuthenticationStatement
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            $id,
+            IDValue::fromString($id),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
-        $subjectLocality = new SubjectLocality('127.0.0.1', 'simplesamlphp.org');
+        $subjectLocality = new SubjectLocality(
+            SAMLStringValue::fromString('127.0.0.1'),
+            SAMLStringValue::fromString('simplesamlphp.org'),
+        );
+
         $authorityBinding = new AuthorityBinding(
-            'samlp:AttributeQuery',
-            'urn:x-simplesamlphp:location',
-            'urn:x-simplesamlphp:binding',
+            QNameValue::fromString('{' . C::NS_SAMLP . '}samlp:AttributeQuery'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:location'),
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:binding'),
         );
 
         return new AuthenticationStatement(
             $subject,
-            C::AC_PASSWORD,
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            SAMLAnyURIValue::fromString(C::AC_PASSWORD),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             $subjectLocality,
             [$authorityBinding],
         );
@@ -291,42 +356,65 @@ private function createAuthenticationStatement(string $id): AuthenticationStatem
      */
     private function createAttributeStatement(string $id): AttributeStatement
     {
-        $scd = new SubjectConfirmationData(2);
+        // Create AttributeStatement
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            $id,
+            IDValue::fromString($id),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
         $attribute = new Attribute(
-            'TheName',
-            'https://example.org/',
-            [new AttributeValue('FirstValue'), new AttributeValue('SecondValue')],
+            SAMLStringValue::fromString('TheName'),
+            SAMLAnyURIValue::fromString('https://example.org/'),
+            [
+                new AttributeValue(
+                    SAMLStringValue::fromString('FirstValue'),
+                ),
+                new AttributeValue(
+                    SAMLStringValue::fromString('SecondValue'),
+                ),
+            ],
         );
 
         return new AttributeStatement(
diff --git a/tests/src/SAML11/XML/saml/NameIdentifierTest.php b/tests/src/SAML11/XML/saml/NameIdentifierTest.php
index 94f4726..6ab8f64 100644
--- a/tests/src/SAML11/XML/saml/NameIdentifierTest.php
+++ b/tests/src/SAML11/XML/saml/NameIdentifierTest.php
@@ -4,14 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractNameIdentifierType;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
+use SimpleSAML\SAML11\XML\saml\{AbstractNameIdentifierType, AbstractSamlElement, NameIdentifier};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -21,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(NameIdentifier::class)]
 #[CoversClass(AbstractNameIdentifierType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -34,8 +33,6 @@ final class NameIdentifierTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = NameIdentifier::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -52,9 +49,9 @@ public static function setUpBeforeClass(): void
     public function testMarshalling(): void
     {
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            StringValue::fromString('TheNameIDValue'),
+            StringValue::fromString('TheNameQualifier'),
+            AnyURIValue::fromString('urn:the:format'),
         );
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/saml/StatementTest.php b/tests/src/SAML11/XML/saml/StatementTest.php
index aa9653b..aae7ca2 100644
--- a/tests/src/SAML11/XML/saml/StatementTest.php
+++ b/tests/src/SAML11/XML/saml/StatementTest.php
@@ -4,20 +4,21 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatementType;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\UnknownStatement;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractSamlElement,
+    AbstractStatement,
+    AbstractStatementType,
+    Audience,
+    UnknownStatement,
+};
 use SimpleSAML\Test\SAML11\CustomStatement;
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -27,6 +28,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(UnknownStatement::class)]
 #[CoversClass(AbstractStatement::class)]
 #[CoversClass(AbstractStatementType::class)]
@@ -77,7 +79,11 @@ public static function tearDownAfterClass(): void
     public function testMarshalling(): void
     {
         $statement = new CustomStatement(
-            [new Audience('urn:some:audience')],
+            [
+                new Audience(
+                    AnyURIValue::fromString('urn:some:audience'),
+                ),
+            ],
         );
 
         $this->assertEquals(
@@ -120,7 +126,10 @@ public function testUnmarshallingUnregistered(): void
         $statement = AbstractStatement::fromXML($element);
 
         $this->assertInstanceOf(UnknownStatement::class, $statement);
-        $this->assertEquals('urn:x-simplesamlphp:namespace:UnknownStatementType', $statement->getXsiType());
+        $this->assertEquals(
+            '{urn:x-simplesamlphp:namespace}ssp:UnknownStatementType',
+            $statement->getXsiType()->getRawValue(),
+        );
 
         $chunk = $statement->getRawStatement();
         $this->assertEquals('saml', $chunk->getPrefix());
diff --git a/tests/src/SAML11/XML/saml/SubjectConfirmationDataTest.php b/tests/src/SAML11/XML/saml/SubjectConfirmationDataTest.php
index 439e064..d8d306a 100644
--- a/tests/src/SAML11/XML/saml/SubjectConfirmationDataTest.php
+++ b/tests/src/SAML11/XML/saml/SubjectConfirmationDataTest.php
@@ -4,15 +4,15 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
+use SimpleSAML\SAML11\Exception\ProtocolViolationException;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\SAML11\XML\saml\{AbstractSamlElement, NameIdentifier, SubjectConfirmationData};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\IntegerValue;
 
 use function dirname;
 use function strval;
@@ -22,6 +22,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(SubjectConfirmationData::class)]
 #[CoversClass(AbstractSamlElement::class)]
 final class SubjectConfirmationDataTest extends TestCase
@@ -33,8 +34,6 @@ final class SubjectConfirmationDataTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = SubjectConfirmationData::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -51,9 +50,11 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData(2);
-        $this->assertIsInt($scd->getValue());
-        $this->assertEquals(2, $scd->getValue());
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
+        $this->assertInstanceOf(IntegerValue::class, $scd->getValue());
+        $this->assertEquals('2', strval($scd->getValue()));
         $this->assertEquals('xs:integer', $scd->getXsiType());
 
         $this->assertEquals(
@@ -68,9 +69,12 @@ public function testMarshalling(): void
      */
     public function testMarshallingString(): void
     {
-        $scd = new SubjectConfirmationData('value');
+        $scd = new SubjectConfirmationData(
+            StringValue::fromString('value'),
+        );
 
-        $this->assertEquals('value', $scd->getValue());
+        $this->assertInstanceOf(StringValue::class, $scd->getValue());
+        $this->assertEquals('value', strval($scd->getValue()));
         $this->assertEquals('xs:string', $scd->getXsiType());
     }
 
@@ -101,15 +105,10 @@ public function testMarshallingNull(): void
      */
     public function testEmptyStringAttribute(): void
     {
-        $scd = new SubjectConfirmationData('');
-        $xmlRepresentation = clone self::$xmlRepresentation;
-        $xmlRepresentation->documentElement->textContent = '';
-//        $this->assertEqualXMLStructure(
-//            $this->xmlRepresentation->documentElement,
-//            $scd->toXML(),
-//        );
-        $this->assertEquals('', $scd->getValue());
-        $this->assertEquals('xs:string', $scd->getXsiType());
+        $this->expectException(ProtocolViolationException::class);
+        new SubjectConfirmationData(
+            StringValue::fromString(''),
+        );
     }
 
 
@@ -132,7 +131,7 @@ public function testUnmarshallingNameID(): void
 
         $this->assertInstanceOf(NameIdentifier::class, $value);
 
-        $this->assertEquals('abcd-some-value-xyz', $value->getContent());
+        $this->assertEquals('abcd-some-value-xyz', $value->getValue());
         $this->assertEquals('urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified', $value->getFormat());
         $this->assertXmlStringEqualsXmlString($document->saveXML(), $scd->toXML()->ownerDocument?->saveXML());
     }
diff --git a/tests/src/SAML11/XML/saml/SubjectConfirmationTest.php b/tests/src/SAML11/XML/saml/SubjectConfirmationTest.php
index 2854a27..f358acb 100644
--- a/tests/src/SAML11/XML/saml/SubjectConfirmationTest.php
+++ b/tests/src/SAML11/XML/saml/SubjectConfirmationTest.php
@@ -4,23 +4,27 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectConfirmationType;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\Type\AnyURIValue as SAMLAnyURIValue;
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractSamlElement,
+    AbstractSubjectConfirmationType,
+    ConfirmationMethod,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, IntegerValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -30,6 +34,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(SubjectConfirmation::class)]
 #[CoversClass(AbstractSubjectConfirmationType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -49,8 +54,6 @@ final class SubjectConfirmationTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = SubjectConfirmation::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -91,26 +94,41 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'fed654',
+            IDValue::fromString('fed654'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
diff --git a/tests/src/SAML11/XML/saml/SubjectLocalityTest.php b/tests/src/SAML11/XML/saml/SubjectLocalityTest.php
index 210f964..dc2851e 100644
--- a/tests/src/SAML11/XML/saml/SubjectLocalityTest.php
+++ b/tests/src/SAML11/XML/saml/SubjectLocalityTest.php
@@ -4,14 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectLocalityType;
-use SimpleSAML\SAML11\XML\saml\SubjectLocality;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\SAML11\XML\saml\{AbstractSamlElement, AbstractSubjectLocalityType, SubjectLocality};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -21,6 +19,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(SubjectLocality::class)]
 #[CoversClass(AbstractSubjectLocalityType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -34,8 +33,6 @@ final class SubjectLocalityTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = SubjectLocality::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -52,7 +49,10 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $sl = new SubjectLocality('127.0.0.1', 'simplesamlphp.org');
+        $sl = new SubjectLocality(
+            StringValue::fromString('127.0.0.1'),
+            StringValue::fromString('simplesamlphp.org'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/saml/SubjectStatementTest.php b/tests/src/SAML11/XML/saml/SubjectStatementTest.php
index 3ce619b..515783d 100644
--- a/tests/src/SAML11/XML/saml/SubjectStatementTest.php
+++ b/tests/src/SAML11/XML/saml/SubjectStatementTest.php
@@ -4,32 +4,39 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractStatementType;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectStatement;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectStatementType;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\saml\UnknownSubjectStatement;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractSamlElement,
+    AbstractStatementType,
+    AbstractSubjectStatement,
+    AbstractSubjectStatementType,
+    Audience,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+    UnknownSubjectStatement,
+};
 use SimpleSAML\Test\SAML11\CustomSubjectStatement;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, IntegerValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -39,6 +46,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(AbstractSubjectStatement::class)]
 #[CoversClass(AbstractSubjectStatementType::class)]
 #[CoversClass(AbstractStatementType::class)]
@@ -115,38 +123,55 @@ public static function tearDownAfterClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'SubjectStatementID',
+            IDValue::fromString('SubjectStatementID'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
         $subjectStatement = new CustomSubjectStatement($subject, [$audience]);
 
         $this->assertEquals(
@@ -187,8 +212,8 @@ public function testUnmarshallingUnregistered(): void
 
         $this->assertInstanceOf(UnknownSubjectStatement::class, $subjectStatement);
         $this->assertEquals(
-            'urn:x-simplesamlphp:namespace:UnknownSubjectStatementType',
-            $subjectStatement->getXsiType(),
+            '{urn:x-simplesamlphp:namespace}ssp:UnknownSubjectStatementType',
+            $subjectStatement->getXsiType()->getRawValue(),
         );
 
         $chunk = $subjectStatement->getRawSubjectStatement();
diff --git a/tests/src/SAML11/XML/saml/SubjectTest.php b/tests/src/SAML11/XML/saml/SubjectTest.php
index b4e8feb..81ee6ac 100644
--- a/tests/src/SAML11/XML/saml/SubjectTest.php
+++ b/tests/src/SAML11/XML/saml/SubjectTest.php
@@ -4,25 +4,32 @@
 
 namespace SimpleSAML\Test\SAML11\XML\saml;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AbstractSamlElement;
-use SimpleSAML\SAML11\XML\saml\AbstractSubjectType;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    AbstractSamlElement,
+    AbstractSubjectType,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, IntegerValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -32,6 +39,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('saml')]
 #[CoversClass(Subject::class)]
 #[CoversClass(AbstractSubjectType::class)]
 #[CoversClass(AbstractSamlElement::class)]
@@ -51,8 +59,6 @@ final class SubjectTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-assertion-1.1.xsd';
-
         self::$testedClass = Subject::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -93,34 +99,49 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData(2);
+        $scd = new SubjectConfirmationData(
+            IntegerValue::fromString('2'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'fed654',
+            IDValue::fromString('fed654'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
diff --git a/tests/src/SAML11/XML/samlp/AssertionArtifactTest.php b/tests/src/SAML11/XML/samlp/AssertionArtifactTest.php
index 86750d2..5986016 100644
--- a/tests/src/SAML11/XML/samlp/AssertionArtifactTest.php
+++ b/tests/src/SAML11/XML/samlp/AssertionArtifactTest.php
@@ -4,13 +4,12 @@
 
 namespace Simplesamlp\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\AssertionArtifact;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\SAML11\XML\samlp\{AbstractSamlpElement, AssertionArtifact};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -20,6 +19,7 @@
  *
  * @package simplesamlpphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(AssertionArtifact::class)]
 #[CoversClass(AbstractSamlpElement::class)]
 final class AssertionArtifactTest extends TestCase
@@ -32,8 +32,6 @@ final class AssertionArtifactTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = AssertionArtifact::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -50,7 +48,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $assertionArtifact = new AssertionArtifact('AAEbuqrPjR1XORIHk5YAV8I4sM0nKP2CLV+h1CMiWbnkaWvvlJ0g4Ess');
+        $assertionArtifact = new AssertionArtifact(
+            StringValue::fromString('AAEbuqrPjR1XORIHk5YAV8I4sM0nKP2CLV+h1CMiWbnkaWvvlJ0g4Ess'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/samlp/AttributeQueryTest.php b/tests/src/SAML11/XML/samlp/AttributeQueryTest.php
index aac351b..6a27d4e 100644
--- a/tests/src/SAML11/XML/samlp/AttributeQueryTest.php
+++ b/tests/src/SAML11/XML/samlp/AttributeQueryTest.php
@@ -4,29 +4,38 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\AttributeDesignator;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\samlp\AbstractAttributeQueryType;
-use SimpleSAML\SAML11\XML\samlp\AbstractQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\AbstractSubjectQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AttributeQuery;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    AttributeDesignator,
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractAttributeQueryType,
+    AbstractQueryAbstractType,
+    AbstractSamlpElement,
+    AbstractSubjectQueryAbstractType,
+    AttributeQuery,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -36,6 +45,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(AttributeQuery::class)]
 #[CoversClass(AbstractAttributeQueryType::class)]
 #[CoversClass(AbstractSubjectQueryAbstractType::class)]
@@ -56,8 +66,6 @@ final class AttributeQueryTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = AttributeQuery::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -98,43 +106,64 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData('phpunit');
+        $scd = new SubjectConfirmationData(
+            SAMLStringValue::fromString('phpunit'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'fed654',
+            IDValue::fromString('fed654'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
         $attributeQuery = new AttributeQuery(
             $subject,
-            'urn:some:resource',
+            SAMLAnyURIValue::fromString('urn:some:resource'),
             [
-                new AttributeDesignator('TheName', 'https://example.org/'),
-                new AttributeDesignator('TheOtherName', 'https://example.org/'),
+                new AttributeDesignator(
+                    SAMLStringValue::fromString('TheName'),
+                    SAMLAnyURIValue::fromString('https://example.org/'),
+                ),
+                new AttributeDesignator(
+                    SAMLStringValue::fromString('TheOtherName'),
+                    SAMLAnyURIValue::fromString('https://example.org/'),
+                ),
             ],
         );
 
diff --git a/tests/src/SAML11/XML/samlp/AuthenticationQueryTest.php b/tests/src/SAML11/XML/samlp/AuthenticationQueryTest.php
index 5db861f..580c8e0 100644
--- a/tests/src/SAML11/XML/samlp/AuthenticationQueryTest.php
+++ b/tests/src/SAML11/XML/samlp/AuthenticationQueryTest.php
@@ -4,29 +4,38 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\samlp\AbstractAuthenticationQueryType;
-use SimpleSAML\SAML11\XML\samlp\AbstractQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\AbstractSubjectQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AuthenticationQuery;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractAuthenticationQueryType,
+    AbstractQueryAbstractType,
+    AbstractSamlpElement,
+    AbstractSubjectQueryAbstractType,
+    AuthenticationQuery,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue, StringValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -36,6 +45,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(AuthenticationQuery::class)]
 #[CoversClass(AbstractAuthenticationQueryType::class)]
 #[CoversClass(AbstractSubjectQueryAbstractType::class)]
@@ -56,8 +66,6 @@ final class AuthenticationQueryTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = AuthenticationQuery::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -98,40 +106,55 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData('phpunit');
+        $scd = new SubjectConfirmationData(
+            SAMLStringValue::fromString('phpunit'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'fed654',
+            IDValue::fromString('fed654'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
         $authnQuery = new AuthenticationQuery(
             $subject,
-            C::AC_PASSWORD,
+            SAMLAnyURIValue::fromString(C::AC_PASSWORD),
         );
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/samlp/AuthorizationDecisionQueryTest.php b/tests/src/SAML11/XML/samlp/AuthorizationDecisionQueryTest.php
index c573c42..936e7cb 100644
--- a/tests/src/SAML11/XML/samlp/AuthorizationDecisionQueryTest.php
+++ b/tests/src/SAML11/XML/samlp/AuthorizationDecisionQueryTest.php
@@ -4,40 +4,55 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\saml\Action;
-use SimpleSAML\SAML11\XML\saml\Assertion;
-use SimpleSAML\SAML11\XML\saml\AssertionIDReference;
-use SimpleSAML\SAML11\XML\saml\AttributeStatement;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AudienceRestrictionCondition;
-use SimpleSAML\SAML11\XML\saml\AuthenticationStatement;
-use SimpleSAML\SAML11\XML\saml\Conditions;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\DoNotCacheCondition;
-use SimpleSAML\SAML11\XML\saml\Evidence;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\samlp\AbstractAuthorizationDecisionQueryType;
-use SimpleSAML\SAML11\XML\samlp\AbstractQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\AbstractSubjectQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AuthorizationDecisionQuery;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\Type\{
+    AnyURIValue as SAMLAnyURIValue,
+    DateTimeValue as SAMLDateTimeValue,
+    StringValue as SAMLStringValue,
+};
+use SimpleSAML\SAML11\XML\saml\{
+    Action,
+    Assertion,
+    AssertionIDReference,
+    AttributeStatement,
+    Audience,
+    AudienceRestrictionCondition,
+    AuthenticationStatement,
+    Conditions,
+    ConfirmationMethod,
+    DoNotCacheCondition,
+    Evidence,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractAuthorizationDecisionQueryType,
+    AbstractQueryAbstractType,
+    AbstractSamlpElement,
+    AbstractSubjectQueryAbstractType,
+    AuthorizationDecisionQuery,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{
+    Base64BinaryValue,
+    IDValue,
+    NCNameValue,
+    NonNegativeIntegerValue,
+    StringValue,
+};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -47,6 +62,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(AuthorizationDecisionQuery::class)]
 #[CoversClass(AbstractAuthorizationDecisionQueryType::class)]
 #[CoversClass(AbstractSubjectQueryAbstractType::class)]
@@ -85,8 +101,6 @@ final class AuthorizationDecisionQueryTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = AuthorizationDecisionQuery::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -151,41 +165,60 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData('phpunit');
+        $scd = new SubjectConfirmationData(
+            SAMLStringValue::fromString('phpunit'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'fed654',
+            IDValue::fromString('fed654'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    SAMLAnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            SAMLStringValue::fromString('TheNameIDValue'),
+            SAMLStringValue::fromString('TheNameQualifier'),
+            SAMLAnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
 
-        $assertionIDReference = new AssertionIDReference('_Test');
+        $assertionIDReference = new AssertionIDReference(
+            NCNameValue::fromString('_Test'),
+        );
 
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            SAMLAnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
         $audienceRestrictionCondition = new AudienceRestrictionCondition([$audience]);
 
         $doNotCacheCondition = new DoNotCacheCondition();
@@ -194,14 +227,16 @@ public function testMarshalling(): void
             [$audienceRestrictionCondition],
             [$doNotCacheCondition],
             [],
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
-            new DateTimeImmutable('2023-01-24T09:47:26Z'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:47:26Z'),
         );
 
         $assertion = new Assertion(
-            '_abc123',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('_abc123'),
+            SAMLStringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            SAMLDateTimeValue::fromString('2023-01-24T09:42:26Z'),
             $conditions,
             null, // advice
             [
@@ -214,10 +249,13 @@ public function testMarshalling(): void
 
         $authorizationDecisionQuery = new AuthorizationDecisionQuery(
             $subject,
-            'urn:some:resource',
+            SAMLAnyURIValue::fromString('urn:some:resource'),
             $evidence,
             [
-                new Action('urn:x-simplesamlphp:action', 'urn:x-simplesamlphp:namespace'),
+                new Action(
+                    SAMLStringValue::fromString('urn:x-simplesamlphp:action'),
+                    SAMLAnyURIValue::fromString('urn:x-simplesamlphp:namespace'),
+                ),
             ],
         );
 
diff --git a/tests/src/SAML11/XML/samlp/QueryTest.php b/tests/src/SAML11/XML/samlp/QueryTest.php
index f46b7f1..7c2762d 100644
--- a/tests/src/SAML11/XML/samlp/QueryTest.php
+++ b/tests/src/SAML11/XML/samlp/QueryTest.php
@@ -4,21 +4,21 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
-use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\samlp\AbstractQuery;
-use SimpleSAML\SAML11\XML\samlp\AbstractQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
-use SimpleSAML\SAML11\XML\samlp\UnknownQuery;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractQuery,
+    AbstractQueryAbstractType,
+    AbstractSamlpElement,
+    StatusMessage,
+    UnknownQuery,
+};
 use SimpleSAML\Test\SAML11\CustomQuery;
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -79,7 +79,11 @@ public static function tearDownAfterClass(): void
     public function testMarshalling(): void
     {
         $query = new CustomQuery(
-            [new StatusMessage('urn:some:audience')],
+            [
+                new StatusMessage(
+                    StringValue::fromString('urn:some:audience'),
+                ),
+            ],
         );
 
         $this->assertEquals(
@@ -102,7 +106,10 @@ public function testUnmarshallingUnregistered(): void
         $query = AbstractQuery::fromXML($element);
 
         $this->assertInstanceOf(UnknownQuery::class, $query);
-        $this->assertEquals('urn:x-simplesamlphp:namespace:UnknownQueryType', $query->getXsiType());
+        $this->assertEquals(
+            '{urn:x-simplesamlphp:namespace}ssp:UnknownQueryType',
+            $query->getXsiType()->getRawValue(),
+        );
 
         $chunk = $query->getRawQuery();
         $this->assertEquals('samlp', $chunk->getPrefix());
diff --git a/tests/src/SAML11/XML/samlp/RespondWithTest.php b/tests/src/SAML11/XML/samlp/RespondWithTest.php
index f260731..64dd880 100644
--- a/tests/src/SAML11/XML/samlp/RespondWithTest.php
+++ b/tests/src/SAML11/XML/samlp/RespondWithTest.php
@@ -4,12 +4,13 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\RespondWith;
+use SimpleSAML\SAML11\Type\AnyURIValue;
+use SimpleSAML\SAML11\XML\samlp\{AbstractSamlpElement, RespondWith};
 use SimpleSAML\XML\DOMDocumentFactory;
 use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\Type\{NCNameValue, QNameValue};
 
 use function dirname;
 use function strval;
@@ -19,6 +20,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(RespondWith::class)]
 #[CoversClass(AbstractSamlpElement::class)]
 final class RespondWithTest extends TestCase
@@ -42,7 +44,13 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $respondWith = new RespondWith(RespondWith::NS_PREFIX . ':RespondWith', RespondWith::NS);
+        $respondWith = new RespondWith(
+            QNameValue::fromParts(
+                NCNameValue::fromString('RespondWith'),
+                AnyURIValue::fromString(RespondWith::NS),
+                NCNameValue::fromString(RespondWith::NS_PREFIX),
+            ),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/samlp/ResponseTest.php b/tests/src/SAML11/XML/samlp/ResponseTest.php
index 785659d..0689e7e 100644
--- a/tests/src/SAML11/XML/samlp/ResponseTest.php
+++ b/tests/src/SAML11/XML/samlp/ResponseTest.php
@@ -4,28 +4,32 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use DateTimeImmutable;
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\Assertion;
-//use SimpleSAML\SAML11\XML\saml\AttributeStatement;
-use SimpleSAML\SAML11\XML\saml\Audience;
-use SimpleSAML\SAML11\XML\saml\AudienceRestrictionCondition;
-use SimpleSAML\SAML11\XML\saml\AuthenticationStatement;
-use SimpleSAML\SAML11\XML\saml\Conditions;
-use SimpleSAML\SAML11\XML\saml\DoNotCacheCondition;
-use SimpleSAML\SAML11\XML\samlp\AbstractResponseAbstractType;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\Response;
-use SimpleSAML\SAML11\XML\samlp\Status;
-use SimpleSAML\SAML11\XML\samlp\StatusCode;
-//use SimpleSAML\SAML11\XML\samlp\StatusDetail;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
+use SimpleSAML\SAML11\Type\{AnyURIValue, DateTimeValue, StringValue};
+use SimpleSAML\SAML11\XML\saml\{
+    Assertion,
+    //AttributeStatement,
+    Audience,
+    AudienceRestrictionCondition,
+    AuthenticationStatement,
+    Conditions,
+    DoNotCacheCondition,
+};
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractResponseAbstractType,
+    AbstractSamlpElement,
+    Response,
+    Status,
+    StatusCode,
+    //StatusDetail,
+    StatusMessage,
+};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{IDValue, NonNegativeIntegerValue, QNameValue};
 
 use function dirname;
 use function strval;
@@ -35,6 +39,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(Response::class)]
 #[CoversClass(AbstractResponseAbstractType::class)]
 #[CoversClass(AbstractSamlpElement::class)]
@@ -50,8 +55,6 @@ final class ResponseTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = Response::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -72,7 +75,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $audience = new Audience('urn:x-simplesamlphp:audience');
+        $audience = new Audience(
+            AnyURIValue::fromString('urn:x-simplesamlphp:audience'),
+        );
         $audienceRestrictionCondition = new AudienceRestrictionCondition([$audience]);
 
         $doNotCacheCondition = new DoNotCacheCondition();
@@ -81,14 +86,16 @@ public function testMarshalling(): void
             [$audienceRestrictionCondition],
             [$doNotCacheCondition],
             [],
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
-            new DateTimeImmutable('2023-01-24T09:47:26Z'),
+            DateTimeValue::fromString('2023-01-24T09:42:26Z'),
+            DateTimeValue::fromString('2023-01-24T09:47:26Z'),
         );
 
         $assertion = new Assertion(
-            '_abc123',
-            'urn:x-simplesamlphp:phpunit',
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('_abc123'),
+            StringValue::fromString('urn:x-simplesamlphp:phpunit'),
+            DateTimeValue::fromString('2023-01-24T09:42:26Z'),
             $conditions,
             null, // advice
             [
@@ -98,23 +105,25 @@ public function testMarshalling(): void
 
         $status = new Status(
             new StatusCode(
-                C::STATUS_RESPONDER,
+                QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_RESPONDER),
                 [
                     new StatusCode(
-                        C::STATUS_REQUEST_DENIED,
+                        QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_REQUEST_DENIED),
                     ),
                 ],
             ),
-            new StatusMessage('Something went wrong'),
+            new StatusMessage(
+                StringValue::fromString('Something went wrong'),
+            ),
         );
 
         $response = new Response(
-            'def456',
+            NonNegativeIntegerValue::fromString('1'),
+            NonNegativeIntegerValue::fromString('1'),
+            IDValue::fromString('def456'),
             $status,
             [$assertion],
-            1,
-            1,
-            new DateTimeImmutable('2023-01-24T09:42:26Z'),
+            DateTimeValue::fromString('2023-01-24T09:42:26Z'),
         );
 
         $this->assertEquals(
diff --git a/tests/src/SAML11/XML/samlp/StatusCodeTest.php b/tests/src/SAML11/XML/samlp/StatusCodeTest.php
index 617e34a..a2cbd82 100644
--- a/tests/src/SAML11/XML/samlp/StatusCodeTest.php
+++ b/tests/src/SAML11/XML/samlp/StatusCodeTest.php
@@ -4,15 +4,13 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
-use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\StatusCode;
+use SimpleSAML\SAML11\XML\samlp\{AbstractSamlpElement, StatusCode};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\QNameValue;
 
 use function dirname;
 use function strval;
@@ -35,8 +33,6 @@ final class StatusCodeTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = StatusCode::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -51,9 +47,11 @@ public function testMarshalling(): void
     {
 
         $statusCode = new StatusCode(
-            C::STATUS_RESPONDER,
+            QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_RESPONDER),
             [
-                new StatusCode(C::STATUS_REQUEST_DENIED),
+                new StatusCode(
+                    QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_REQUEST_DENIED),
+                ),
             ],
         );
 
diff --git a/tests/src/SAML11/XML/samlp/StatusDetailTest.php b/tests/src/SAML11/XML/samlp/StatusDetailTest.php
index 8ca0523..69011fe 100644
--- a/tests/src/SAML11/XML/samlp/StatusDetailTest.php
+++ b/tests/src/SAML11/XML/samlp/StatusDetailTest.php
@@ -4,7 +4,7 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
 use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
@@ -23,6 +23,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(StatusDetail::class)]
 #[CoversClass(AbstractStatusDetailType::class)]
 #[CoversClass(AbstractSamlpElement::class)]
@@ -35,8 +36,6 @@ final class StatusDetailTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = StatusDetail::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
diff --git a/tests/src/SAML11/XML/samlp/StatusMessageTest.php b/tests/src/SAML11/XML/samlp/StatusMessageTest.php
index 7c88c9b..31f2ca8 100644
--- a/tests/src/SAML11/XML/samlp/StatusMessageTest.php
+++ b/tests/src/SAML11/XML/samlp/StatusMessageTest.php
@@ -4,14 +4,12 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
-use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
+use SimpleSAML\SAML11\Type\StringValue;
+use SimpleSAML\SAML11\XML\samlp\{AbstractSamlpElement, StatusMessage};
 use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
 
 use function dirname;
 use function strval;
@@ -33,8 +31,6 @@ final class StatusMessageTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = StatusMessage::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -47,7 +43,9 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshalling(): void
     {
-        $statusMessage = new StatusMessage('Something went wrong');
+        $statusMessage = new StatusMessage(
+            StringValue::fromString('Something went wrong'),
+        );
 
         $this->assertEquals(
             self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
diff --git a/tests/src/SAML11/XML/samlp/StatusTest.php b/tests/src/SAML11/XML/samlp/StatusTest.php
index a649639..6becf49 100644
--- a/tests/src/SAML11/XML/samlp/StatusTest.php
+++ b/tests/src/SAML11/XML/samlp/StatusTest.php
@@ -5,20 +5,21 @@
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
 use DOMDocument;
-use PHPUnit\Framework\Attributes\CoversClass;
-use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\SAML11\Constants as C;
+use SimpleSAML\SAML11\Type\StringValue;
 use SimpleSAML\SAML11\Utils\XPath;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\Status;
-use SimpleSAML\SAML11\XML\samlp\StatusCode;
-use SimpleSAML\SAML11\XML\samlp\StatusDetail;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractSamlpElement,
+    Status,
+    StatusCode,
+    StatusDetail,
+    StatusMessage,
+};
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\QNameValue;
 
 use function dirname;
 use function strval;
@@ -44,8 +45,6 @@ final class StatusTest extends TestCase
      */
     public static function setUpBeforeClass(): void
     {
-        self::$schemaFile = dirname(__FILE__, 6) . '/resources/schemas/oasis-sstc-saml-schema-protocol-1.1.xsd';
-
         self::$testedClass = Status::class;
 
         self::$xmlRepresentation = DOMDocumentFactory::fromFile(
@@ -64,14 +63,16 @@ public function testMarshalling(): void
     {
         $status = new Status(
             new StatusCode(
-                C::STATUS_RESPONDER,
+                QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_RESPONDER),
                 [
                     new StatusCode(
-                        C::STATUS_REQUEST_DENIED,
+                        QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_REQUEST_DENIED),
                     ),
                 ],
             ),
-            new StatusMessage('Something went wrong'),
+            new StatusMessage(
+                StringValue::fromString('Something went wrong'),
+            ),
             StatusDetail::fromXML(
                 DOMDocumentFactory::fromFile(
                     dirname(__FILE__, 5) . '/resources/xml/samlp_StatusDetail.xml',
@@ -92,14 +93,16 @@ public function testMarshallingElementOrdering(): void
     {
         $status = new Status(
             new StatusCode(
-                C::STATUS_RESPONDER,
+                QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_RESPONDER),
                 [
                     new StatusCode(
-                        C::STATUS_REQUEST_DENIED,
+                        QNameValue::fromString('{' . C::NS_SAMLP . '}' . C::STATUS_REQUEST_DENIED),
                     ),
                 ],
             ),
-            new StatusMessage('Something went wrong'),
+            new StatusMessage(
+                StringValue::fromString('Something went wrong'),
+            ),
             new StatusDetail([new Chunk(self::$detail->documentElement)]),
         );
 
diff --git a/tests/src/SAML11/XML/samlp/SubjectQueryTest.php b/tests/src/SAML11/XML/samlp/SubjectQueryTest.php
index 230e4bf..3b8e5db 100644
--- a/tests/src/SAML11/XML/samlp/SubjectQueryTest.php
+++ b/tests/src/SAML11/XML/samlp/SubjectQueryTest.php
@@ -4,32 +4,37 @@
 
 namespace SimpleSAML\Test\SAML11\XML\samlp;
 
-use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\{CoversClass, Group};
 use PHPUnit\Framework\TestCase;
-use SimpleSAML\SAML11\Compat\AbstractContainer;
-use SimpleSAML\SAML11\Compat\ContainerSingleton;
+use SimpleSAML\SAML11\Compat\{AbstractContainer, ContainerSingleton};
 use SimpleSAML\SAML11\Constants as C;
-use SimpleSAML\SAML11\XML\saml\ConfirmationMethod;
-use SimpleSAML\SAML11\XML\saml\NameIdentifier;
-use SimpleSAML\SAML11\XML\saml\Subject;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmation;
-use SimpleSAML\SAML11\XML\saml\SubjectConfirmationData;
-use SimpleSAML\SAML11\XML\samlp\AbstractSamlpElement;
-use SimpleSAML\SAML11\XML\samlp\AbstractSubjectQuery;
-use SimpleSAML\SAML11\XML\samlp\AbstractSubjectQueryAbstractType;
-use SimpleSAML\SAML11\XML\samlp\StatusMessage;
-use SimpleSAML\SAML11\XML\samlp\UnknownSubjectQuery;
+use SimpleSAML\SAML11\Type\{AnyURIValue, StringValue};
+use SimpleSAML\SAML11\XML\saml\{
+    ConfirmationMethod,
+    NameIdentifier,
+    Subject,
+    SubjectConfirmation,
+    SubjectConfirmationData,
+};
+use SimpleSAML\SAML11\XML\samlp\{
+    AbstractSamlpElement,
+    AbstractSubjectQuery,
+    AbstractSubjectQueryAbstractType,
+    StatusMessage,
+    UnknownSubjectQuery,
+};
 use SimpleSAML\Test\SAML11\CustomSubjectQuery;
-use SimpleSAML\XML\Chunk;
-use SimpleSAML\XML\DOMDocumentFactory;
-use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
-use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+use SimpleSAML\XML\{Chunk, DOMDocumentFactory};
+use SimpleSAML\XML\TestUtils\{SchemaValidationTestTrait, SerializableElementTestTrait};
+use SimpleSAML\XML\Type\{Base64BinaryValue, IDValue};
 use SimpleSAML\XMLSecurity\TestUtils\PEMCertificatesMock;
-use SimpleSAML\XMLSecurity\XML\ds\KeyInfo;
-use SimpleSAML\XMLSecurity\XML\ds\KeyName;
-use SimpleSAML\XMLSecurity\XML\ds\X509Certificate;
-use SimpleSAML\XMLSecurity\XML\ds\X509Data;
-use SimpleSAML\XMLSecurity\XML\ds\X509SubjectName;
+use SimpleSAML\XMLSecurity\XML\ds\{
+    KeyInfo,
+    KeyName,
+    X509Certificate,
+    X509Data,
+    X509SubjectName,
+};
 
 use function dirname;
 use function strval;
@@ -39,6 +44,7 @@
  *
  * @package simplesamlphp/saml11
  */
+#[Group('samlp')]
 #[CoversClass(AbstractSubjectQuery::class)]
 #[CoversClass(AbstractSubjectQueryAbstractType::class)]
 #[CoversClass(AbstractSamlpElement::class)]
@@ -116,40 +122,59 @@ public static function tearDownAfterClass(): void
      */
     public function testMarshalling(): void
     {
-        $scd = new SubjectConfirmationData('phpunit');
+        $scd = new SubjectConfirmationData(
+            StringValue::fromString('phpunit'),
+        );
 
         $keyInfo = new KeyInfo(
             [
-                new KeyName('testkey'),
+                new KeyName(
+                    StringValue::fromString('testkey'),
+                ),
                 new X509Data(
                     [
-                        new X509Certificate(self::$certificate),
-                        new X509SubjectName(self::$certData['name']),
+                        new X509Certificate(
+                            Base64BinaryValue::fromString(self::$certificate),
+                        ),
+                        new X509SubjectName(
+                            StringValue::fromString(self::$certData['name']),
+                        ),
                     ],
                 ),
                 new Chunk(DOMDocumentFactory::fromString(
                     '<ssp:Chunk xmlns:ssp="urn:x-simplesamlphp:namespace">some</ssp:Chunk>',
                 )->documentElement),
             ],
-            'fed654',
+            IDValue::fromString('fed654'),
         );
 
         $sc = new SubjectConfirmation(
-            [new ConfirmationMethod('_Test1'), new ConfirmationMethod('_Test2')],
+            [
+                new ConfirmationMethod(
+                    AnyURIValue::fromString('_Test1'),
+                ),
+                new ConfirmationMethod(
+                    AnyURIValue::fromString('_Test2'),
+                ),
+            ],
             $scd,
             $keyInfo,
         );
 
         $nameIdentifier = new NameIdentifier(
-            'TheNameIDValue',
-            'TheNameQualifier',
-            'urn:the:format',
+            StringValue::fromString('TheNameIDValue'),
+            StringValue::fromString('TheNameQualifier'),
+            AnyURIValue::fromString('urn:the:format'),
         );
 
         $subject = new Subject($sc, $nameIdentifier);
         $subjectQuery = new CustomSubjectQuery(
             $subject,
-            [new StatusMessage('urn:some:audience')],
+            [
+                new StatusMessage(
+                    StringValue::fromString('urn:some:audience'),
+                ),
+            ],
         );
 
         $this->assertEquals(
@@ -168,6 +193,7 @@ public function testUnmarshallingUnregistered(): void
     {
         $element = clone self::$xmlRepresentation->documentElement;
         $element->setAttributeNS(C::NS_XSI, 'xsi:type', 'ssp:UnknownSubjectQueryType');
+        $element->setAttributeNS('http://www.w3.org/2000/xmlns/', 'xmlns:ssp', 'urn:x-simplesamlphp:namespace');
 
         // Normalize the DOMElement by importing it into a clean empty document
         $newDoc = DOMDocumentFactory::create();
@@ -177,7 +203,10 @@ public function testUnmarshallingUnregistered(): void
         $subjectQuery = AbstractSubjectQuery::fromXML($element);
 
         $this->assertInstanceOf(UnknownSubjectQuery::class, $subjectQuery);
-        $this->assertEquals('urn:x-simplesamlphp:namespace:UnknownSubjectQueryType', $subjectQuery->getXsiType());
+        $this->assertEquals(
+            '{urn:x-simplesamlphp:namespace}ssp:UnknownSubjectQueryType',
+            $subjectQuery->getXsiType()->getRawValue(),
+        );
 
         $chunk = $subjectQuery->getRawSubjectQuery();
         $this->assertEquals('samlp', $chunk->getPrefix());