Add signature to GMetaData for component signatures

Author: pmai

docs/4___common_content.adoc

@@ -464,10 +464,10 @@ This attribute references another connector by name, that gives the size of this
 [#ssc_metadata]
 ==== MetaData Sequence
 
-image:images/SystemStructureCommon_GMetaData.png[image,width=597,height=146]
+image:images/SystemStructureCommon_GMetaData.png[image,width=597,height=196]
 
-The MetaData element allows the specification of additional meta data for a given resource.
-Multiple (or no) MetaData elements may be present in a given resource.
+The MetaData element allows the specification of additional meta data for a given model element.
+Multiple (or no) MetaData elements may be present in a given model element.
 
 [width="100%",cols="33%,67%",options="header",]
 |===
@@ -531,7 +531,9 @@ In that case there *SHOULD* be a layered specification that defines how embeddin
 
 image:images/SystemStructureCommon_Signature.png[image,width=423,height=534]
 
-This element specifies digital signature information on the meta data referenced by the enclosing MetaData element.
+This element specifies digital signature information on the data or meta data referenced by the enclosing element:
+If the Signature element is contained within a MetaData element, it refers to the meta data referenced by the MetaData element.
+If the Signature element is contained within any other element, it refers to the content of that element.
 
 The Signature element is structured by the following subordinated elements.
 
@@ -557,12 +559,13 @@ This mandatory attribute specifies the MIME type of the signature, which does no
 If no specific MIME type can be indicated, then the type `application/octet-stream` is to be used.
 |source a|
 Optional attribute indicating the source of the signature as a URI (cf. RFC 3986).
-For purposes of the resolution of relative URIs the base URI is the URI of the SSD, if the sourceBase attribute is not specified or is specified as `SSD`, and the URI of the containing model element (e.g. component) if the base attribute is specified as `component`, or the URI of the meta data source if the sourceBase attribute is specified as `metaData`.
+For purposes of the resolution of relative URIs the base URI is the URI of the SSD, if the sourceBase attribute is not specified or is specified as `SSD`, the URI of the containing model element (e.g. component) if the base attribute is specified as `component`, or the URI of the meta data source if the sourceBase attribute is specified as `metaData`.
 
 This allows the specification of signature sources that reside inside the component (for example an FMU), or the meta data through relative URIs.
 
 If the source attribute is missing, the signature *MUST* be provided inline as contents of a Content element, which *MUST NOT* be present otherwise.
 |sourceBase a|
 Defines the base the source URI is resolved against:
 If the attribute is missing or is specified as `SSD`, the source is resolved against the URI of the SSD, if the attribute is specified as `component` the URI is resolved against the (resolved) URI of the model element (e.g. component) source, or if the attribute is specified as `metaData` the URI is resolved against the (resolved) URI of the meta data source.
+The value `metaData` is only valid if the Signature element is contained within a MetaData element.
 |===

docs/images/SystemStructureCommon_GMetaData.png

@@ -350,6 +350,15 @@
                     <xs:attributeGroup ref="ssc:ABaseElement"/>
                 </xs:complexType>
             </xs:element>
+            <xs:element name="Signature" type="ssc:SignatureType" minOccurs="0" maxOccurs="unbounded">
+                <xs:annotation>
+                    <xs:documentation xml:lang="en">
+                        This element can contain digital signature information on the data referenced
+                        by the enclosing element. It is left unspecified what types of signatures
+                        are used and/or available for now.  Multiple or no signature elements may be present.
+                    </xs:documentation>
+                </xs:annotation>
+            </xs:element>
         </xs:sequence>
     </xs:group>
 
@@ -387,20 +396,17 @@
         <xs:attribute name="source" type="xs:anyURI" use="optional">
             <xs:annotation>
                 <xs:documentation xml:lang="en">
-                    This attribute indicates the source of the resource signature as a
+                    This attribute indicates the source of the digital signature as a
                     URI (cf. RFC 3986).  For purposes of the resolution of relative URIs
-                    the base URI is the URI of the STC, if the sourceBase attribute is
-                    not specified or is specified as STC, and the URI of the referenced
-                    resource if the sourceBase attribute is specified as resource.
+                    the base URI is the URI of the SSD, if the sourceBase attribute is
+                    not specified or is specified as SSD, the URI of the  containing model
+                    element (e.g. component) if the sourceBase attribute is specified as
+                    component, or the URI of the meta data source if the sourceBase
+                    attribute is specified as metaData.
 
                     This allows the specification of signature sources that reside
-                    inside the resource (e.g. an FMU) through relative URIs.
-                    
-                    For signatures that are located alongside the STC, relative URIs
-                    without scheme and authority can and should be used to specify the
-                    signature sources.  For signatures that are packaged inside an SSP
-                    that contains this STC, this is mandatory (in this way, the STC
-                    URIs remain valid after unpacking the SSP into the filesystem).
+                    inside the component (for example an FMU), or the meta data
+                    through relative URIs.
 
                     If the source attribute is missing, the signature is provided
                     inline as contents of the Content element, which must not be
@@ -411,16 +417,21 @@
         <xs:attribute name="sourceBase" use="optional" default="SSD">
             <xs:annotation>
                 <xs:documentation xml:lang="en">
-                    Defines the base the source URI is resolved against:  If the attribute
+                    Defines the base the source URI is resolved against: If the attribute
                     is missing or is specified as SSD, the source is resolved against the
-                    URI of the SSD, if the attribute is specified as resource the URI is
-                    resolved against the (resolved) URI of the resource source.
+                    URI of the SSD, if the attribute is specified as component the URI is
+                    resolved against the (resolved) URI of the model element (e.g.
+                    component) source, or if the attribute is specified as metaData the
+                    URI is resolved against the (resolved) URI of the meta data source.
+                    The value metaData is only valid if the Signature element is contained
+                    within a MetaData element.
                 </xs:documentation>
             </xs:annotation>
             <xs:simpleType>
                 <xs:restriction base="xs:string">
                     <xs:enumeration value="SSD"/>
-                    <xs:enumeration value="resource"/>
+                    <xs:enumeration value="component"/>
+                    <xs:enumeration value="metaData"/>
                 </xs:restriction>
             </xs:simpleType>
         </xs:attribute>