add security considerations to SensorML

sensorml/standard/sections/clause_0_front_material.adoc

@@ -28,7 +28,11 @@ SensorML is well-suited for describing sensor model imaging geometries – the S
 
 == Security considerations
 
-No security considerations have been made for this standard.
+SensorML documents will often be used to transmit confidential or sensitive data. Encryption in-transit using HTTPS (i.e. HTTP over TLS/SSL) is thus highly recommended and is now very common practice on the web.
+
+In addition, implementations of this standard may also store confidential or sensitive data (e.g. in a database) for extended periods of time. In this case, encryption at rest is also recommended, especially if data is hosted on a shared infrastructure (e.g. public clouds).
+
+Security constraints for individual documents may be defined as described in <<clause-uml-security-constraints>>.
 
 == Submitters
 

sensorml/standard/sections/clause_7.2_uml_core_abstract_process.adoc

@@ -74,6 +74,7 @@ The classifier property provides a list of possible classifiers that might aid i
 Definitions for a classifier Term might include, for instance, sensorType, observableType, processType, intendedApplication, or missionType. 
 ====
 
+[[clause-uml-security-constraints]]
 ===== Security Constraints
 The model for specification of security constraints shall be based on external security models, such as the Security Banner Marking model of the Intelligence Community Information Security Marking (IC ISM) Standard. The securityConstraints property takes a value of xs:Any which allows various communities and countries to utilize their standard XML encoding for security tags. This security constraint is for the overall document. As will be discussed in the XML encoding, extension points provided with SWE Common Data elements will allow security tagging for individual properties or property aggregates.
 

sensorml/standard/sections/clause_8.5_json_physical_system.adoc

@@ -19,7 +19,7 @@ requirement:: /req/json-physical-system/schema-valid
 
 ==== PhysicalSystem
 
-The `PhysicalSystem.json` schema is the JSON schema implementation of the `PhysicalSystem` UML class defined in <<uml_physical_systems>>.
+The `PhysicalSystem.json` schema is the JSON schema implementation of the `PhysicalSystem` UML class defined in <<uml_physical_system>>.
 
 [requirement,model=ogc]
 ====

sensorml/standard/sections/clause_8_json_implementation.adoc

@@ -3,8 +3,8 @@
 
 This standard defines a normative JSON implementation of the conceptual models presented in <<OGC-SML,SensorML 2.1>> and in the following clauses of this document:
 
-- <<clause_model_deployment,style=full%>>
-- <<clause_model_derived_property,style=full%>>
+- <<uml_deployment,style=full%>>
+- <<uml_derived_property,style=full%>>
 - <<clause_model_3dpose,style=full%>>
 
 The standardization target type for all requirements classes in this clause is a JSON instance document that seeks compliance with this JSON encoding model.