diff --git a/Classes/ViewHelpers/ContainsObjectWithUidViewHelper.php b/Classes/ViewHelpers/ContainsObjectWithUidViewHelper.php
index a1f2d71..6b06886 100755
--- a/Classes/ViewHelpers/ContainsObjectWithUidViewHelper.php
+++ b/Classes/ViewHelpers/ContainsObjectWithUidViewHelper.php
@@ -5,6 +5,16 @@
 use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
 use TYPO3\CMS\Extbase\Persistence\ObjectStorage;
 
+/**
+ * This file is part of the "Participants" Extension for TYPO3 CMS.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * (c) 2024 C. Gogolin <service@cylancer.net>
+ *
+ * @package Cylancer\Participants\ViewHelpers
+ */
 class ContainsObjectWithUidViewHelper extends AbstractViewHelper
 {
 
diff --git a/Classes/ViewHelpers/IcsBlankLineEncoderViewHelper.php b/Classes/ViewHelpers/IcsBlankLineEncoderViewHelper.php
new file mode 100644
index 0000000..5592fd8
--- /dev/null
+++ b/Classes/ViewHelpers/IcsBlankLineEncoderViewHelper.php
@@ -0,0 +1,40 @@
+<?php
+namespace Cylancer\Participants\ViewHelpers;
+
+use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
+
+/**
+ * This file is part of the "Participants" Extension for TYPO3 CMS.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * (c) 2024 C. Gogolin <service@cylancer.net>
+ *
+ * @package Cylancer\Participants\ViewHelpers
+ */
+class IcsBlankLineEncoderViewHelper extends AbstractViewHelper
+{
+
+    public function initializeArguments()
+    {
+        $this->registerArgument('value', '*', 'The value ', true);
+    }
+
+    /**
+     * Escapes special characters with their escaped counterparts as needed using PHPs htmlspecialchars() function.
+     *
+     * @return string the altered string
+     * @see http://www.php.net/manual/function.htmlspecialchars.php
+     * @api
+     */
+    public function render()
+    {
+        $value = $this->arguments['value'];
+        if ($value === null) {
+            $value = $this->renderChildren();
+        }
+        return str_replace("\\n\\n", "\\n \\n", str_replace(["\r\n","\r","\n"], "\\n", strip_tags($value)));
+    }
+
+}
diff --git a/Classes/ViewHelpers/InArrayViewHelper.php b/Classes/ViewHelpers/InArrayViewHelper.php
index 4041035..cf9d3c7 100755
--- a/Classes/ViewHelpers/InArrayViewHelper.php
+++ b/Classes/ViewHelpers/InArrayViewHelper.php
@@ -4,6 +4,16 @@
 use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
 use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
 
+/**
+ * This file is part of the "Participants" Extension for TYPO3 CMS.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * (c) 2024 C. Gogolin <service@cylancer.net>
+ *
+ * @package Cylancer\Participants\ViewHelpers
+ */
 class InArrayViewHelper extends AbstractViewHelper
 {
 
diff --git a/Resources/Private/Layouts/ICS.html b/Resources/Private/Layouts/ICS.html
new file mode 100644
index 0000000..8d5af18
--- /dev/null
+++ b/Resources/Private/Layouts/ICS.html
@@ -0,0 +1 @@
+<f:render section="content" />
\ No newline at end of file
diff --git a/Resources/Private/Layouts/ICS.txt b/Resources/Private/Layouts/ICS.txt
new file mode 100644
index 0000000..8d5af18
--- /dev/null
+++ b/Resources/Private/Layouts/ICS.txt
@@ -0,0 +1 @@
+<f:render section="content" />
\ No newline at end of file
diff --git a/Resources/Private/Partials/DutyRoster/DefaultICalendarEntries.html b/Resources/Private/Partials/DutyRoster/DefaultICalendarEntries.html
index 0a4427d..d7c730c 100755
--- a/Resources/Private/Partials/DutyRoster/DefaultICalendarEntries.html
+++ b/Resources/Private/Partials/DutyRoster/DefaultICalendarEntries.html
@@ -30,6 +30,6 @@
 DTSTART;<f:if condition="{event.fullDay}"><f:then>VALUE=DATE</f:then><f:else>TZID=Europe/Berlin</f:else></f:if>:<f:format.date format="%Y%m%d" >{event.date}</f:format.date><f:if condition="!{event.fullDay}"><f:format.date format="T%H%M%S" >{event.time}</f:format.date></f:if>
 DTEND;<f:if condition="{event.fullDay}"><f:then>VALUE=DATE</f:then><f:else>TZID=Europe/Berlin</f:else></f:if>:<f:if condition="{event.fullDay}"><f:then><f:format.date format="%Y%m%d" base="{event.date}"> +1 day</f:format.date></f:then><f:else><f:format.date format="%Y%m%dT%H%M%S" base="{event.dateTime}"> +{event.duration} hours</f:format.date></f:else></f:if>
 SUMMARY:🚒 {event.eventType.title -> f:format.htmlspecialchars()}
-DESCRIPTION:<f:for each="{event.visiblePublicUsergroups}" as="ug"  iteration="iter">{ug.title}<f:if condition="!{iter.isLast}">, </f:if></f:for><f:if condition="{event.description}"> ( {event.description -> f:format.stripTags()} )</f:if>
+DESCRIPTION:<f:for each="{event.visiblePublicUsergroups}" as="ug"  iteration="iter">{ug.title}<f:if condition="!{iter.isLast}">, </f:if></f:for><f:if condition="{event.description}"> ( {event.description -> c:icsBlankLineEncoder()} )</f:if>
 END:VEVENT
 </f:for></f:if>END:VCALENDAR
diff --git a/Resources/Private/Partials/PersonalDutyRoster/DefaultICalendarEntries.html b/Resources/Private/Partials/PersonalDutyRoster/DefaultICalendarEntries.html
index 63648fe..7378030 100755
--- a/Resources/Private/Partials/PersonalDutyRoster/DefaultICalendarEntries.html
+++ b/Resources/Private/Partials/PersonalDutyRoster/DefaultICalendarEntries.html
@@ -30,6 +30,6 @@
 DTSTART;<f:if condition="{commitment.event.fullDay}"><f:then>VALUE=DATE</f:then><f:else>TZID=Europe/Berlin</f:else></f:if>:<f:format.date format="%Y%m%d" >{commitment.event.date}</f:format.date><f:if condition="!{commitment.event.fullDay}"><f:format.date format="T%H%M%S" >{commitment.event.time}</f:format.date></f:if>
 DTEND;<f:if condition="{commitment.event.fullDay}"><f:then>VALUE=DATE</f:then><f:else>TZID=Europe/Berlin</f:else></f:if>:<f:if condition="{commitment.event.fullDay}"><f:then><f:format.date format="%Y%m%d" base="{commitment.event.date}"> +1 day</f:format.date></f:then><f:else><f:format.date format="%Y%m%dT%H%M%S" base="{commitment.event.dateTime}"> +{commitment.event.duration} hours</f:format.date></f:else></f:if>
 SUMMARY:🚒 {commitment.event.eventType.title -> f:format.htmlspecialchars()}
-DESCRIPTION:<f:for each="{commitment.event.visiblePublicUsergroups}" as="ug"  iteration="iter">{ug.title}<f:if condition="!{iter.isLast}">, </f:if></f:for><f:if condition="{commitment.event.description}"> ( {commitment.event.description -> f:format.stripTags()} )</f:if>
+DESCRIPTION:<f:for each="{commitment.event.visiblePublicUsergroups}" as="ug"  iteration="iter">{ug.title}<f:if condition="!{iter.isLast}">, </f:if></f:for><f:if condition="{commitment.event.description}"> ( {commitment.event.description -> c:icsBlankLineEncoder()} )</f:if>
 END:VEVENT
 </f:for></f:if>END:VCALENDAR
diff --git a/Resources/Private/Templates/DutyRoster/DownloadIcs.html b/Resources/Private/Templates/DutyRoster/DownloadIcs.html
index 073b1ed..8b68e31 100755
--- a/Resources/Private/Templates/DutyRoster/DownloadIcs.html
+++ b/Resources/Private/Templates/DutyRoster/DownloadIcs.html
@@ -1 +1,12 @@
-<f:render partial="DutyRoster/DefaultICalendarEntries" arguments="{_all}" />
\ No newline at end of file
+<!DOCTYPE html PUBLIC "-//WC//DTD XHTML . Strict//EN"
+	"http://www.w.org/TR/xhtml/DTD/xhtml-strict.dtd">
+<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers" xmlns:c="http://typo3.org/ns/Cylancer/Participants/ViewHelpers"
+	data-namespace-typo3-fluid="true" xmlns="http://www.w.org//xhtml" xml:lang="en" lang="en"
+>
+<head>
+<meta http-equiv="content-type" content="text/html;charset=utf-8" />
+</head>
+<body>
+	<f:layout name="ICS" />
+	<f:section name="content"><f:render partial="DutyRoster/DefaultICalendarEntries" arguments="{_all}" /></f:section>
+</body></html>
\ No newline at end of file
diff --git a/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedCalendarEntries.html b/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedCalendarEntries.html
index 78ca2de..e1682be 100755
--- a/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedCalendarEntries.html
+++ b/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedCalendarEntries.html
@@ -1 +1,12 @@
-<f:render partial="personalDutyRoster/DefaultICalendarEntries" arguments="{_all}" />
+<!DOCTYPE html PUBLIC "-//WC//DTD XHTML . Strict//EN"
+	"http://www.w.org/TR/xhtml/DTD/xhtml-strict.dtd">
+<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers" xmlns:c="http://typo3.org/ns/Cylancer/Participants/ViewHelpers"
+	data-namespace-typo3-fluid="true" xmlns="http://www.w.org//xhtml" xml:lang="en" lang="en"
+>
+<head>
+<meta http-equiv="content-type" content="text/html;charset=utf-8" />
+</head>
+<body>
+	<f:layout name="ICS" />
+	<f:section name="content"><f:render partial="personalDutyRoster/DefaultICalendarEntries" arguments="{_all}" /></f:section>
+</body></html>
\ No newline at end of file
diff --git a/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedVisibleCalendarEntries.html b/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedVisibleCalendarEntries.html
index 78ca2de..e1682be 100755
--- a/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedVisibleCalendarEntries.html
+++ b/Resources/Private/Templates/PersonalDutyRoster/DownloadAllPromisedVisibleCalendarEntries.html
@@ -1 +1,12 @@
-<f:render partial="personalDutyRoster/DefaultICalendarEntries" arguments="{_all}" />
+<!DOCTYPE html PUBLIC "-//WC//DTD XHTML . Strict//EN"
+	"http://www.w.org/TR/xhtml/DTD/xhtml-strict.dtd">
+<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers" xmlns:c="http://typo3.org/ns/Cylancer/Participants/ViewHelpers"
+	data-namespace-typo3-fluid="true" xmlns="http://www.w.org//xhtml" xml:lang="en" lang="en"
+>
+<head>
+<meta http-equiv="content-type" content="text/html;charset=utf-8" />
+</head>
+<body>
+	<f:layout name="ICS" />
+	<f:section name="content"><f:render partial="personalDutyRoster/DefaultICalendarEntries" arguments="{_all}" /></f:section>
+</body></html>
\ No newline at end of file
diff --git a/Resources/Private/Templates/PersonalDutyRoster/DownloadAllVisibleCalendarEntries.html b/Resources/Private/Templates/PersonalDutyRoster/DownloadAllVisibleCalendarEntries.html
index 78ca2de..e1682be 100755
--- a/Resources/Private/Templates/PersonalDutyRoster/DownloadAllVisibleCalendarEntries.html
+++ b/Resources/Private/Templates/PersonalDutyRoster/DownloadAllVisibleCalendarEntries.html
@@ -1 +1,12 @@
-<f:render partial="personalDutyRoster/DefaultICalendarEntries" arguments="{_all}" />
+<!DOCTYPE html PUBLIC "-//WC//DTD XHTML . Strict//EN"
+	"http://www.w.org/TR/xhtml/DTD/xhtml-strict.dtd">
+<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers" xmlns:c="http://typo3.org/ns/Cylancer/Participants/ViewHelpers"
+	data-namespace-typo3-fluid="true" xmlns="http://www.w.org//xhtml" xml:lang="en" lang="en"
+>
+<head>
+<meta http-equiv="content-type" content="text/html;charset=utf-8" />
+</head>
+<body>
+	<f:layout name="ICS" />
+	<f:section name="content"><f:render partial="personalDutyRoster/DefaultICalendarEntries" arguments="{_all}" /></f:section>
+</body></html>
\ No newline at end of file
diff --git a/ext_emconf.php b/ext_emconf.php
index cb8b6e3..539f84b 100755
--- a/ext_emconf.php
+++ b/ext_emconf.php
@@ -14,7 +14,7 @@
     'uploadfolder' => 0,
     'createDirs' => '',
     'clearCacheOnLoad' => 1,
-    'version' => '3.7.9',
+    'version' => '3.7.10',
     'constraints' => [
         'depends' => [
             'typo3' => '11.5.0-11.5.99',
@@ -30,6 +30,7 @@
  * Change log: 
  * 
 
+3.7.10  :: Fix : Repair the (personal) duty roster iCal export file: simple blank lines are not allowed. iCal needs a special coding. 
 3.7.9   :: Fix : Fix the default user setting for automatic apply commitments.
 3.7.8   :: Fix : Fix the return value type in the frontend user service.
 3.7.7   :: Fix : Adapts the personal duty roster folter column counts.