Address PR feedback to wrap up.

usnistgov#1052 (review)
usnistgov#1052 (comment)

src/metaschema/oscal_metadata_metaschema.xml

@@ -774,10 +774,6 @@
             <formal-name>Action Responsible Role Identifier</formal-name>
             <description>Identifier of the approving role in the responsible party.</description>
         </define-flag>
-        <define-flag name="party-uuid" as-type="token" required="yes">
-            <formal-name>Action Party Universally Unique Identifier</formal-name>
-            <description>The universally unique identifier of the party responsible for the action.</description>
-        </define-flag>
         <define-flag name="date" as-type="dateTime-with-timezone">
             <formal-name>Action Occurrence Date</formal-name>
             <description>The date and time when the action occurred.</description>
@@ -793,13 +789,11 @@
                 <p>Provides a means to segment the value space for the <code>type</code>, so that different organizations and individuals can assert control over the allowed <code>action</code>'s <code>type</code>. This allows the semantics associated with a given <code>type</code> to be defined on an organization-by-organization basis.</p>
                 <p>An organization MUST use a URI that they have control over. e.g., a domain registered to the organization in a URI, a registered uniform resource names (URN) namespace.</p>
             </remarks>
-            <constraint>
-               <allowed-values allow-other="yes">
-                  <enum value="http://csrc.nist.gov/ns/oscal">This value identifies action types defined in the NIST OSCAL namespace.</enum>
-               </allowed-values>
-            </constraint>
          </define-flag>
         <model>
+            <assembly ref="responsible-party" max-occurs="unbounded">
+                <group-as name="responsible-parties" in-json="ARRAY"/>
+              </assembly>
             <assembly ref="property" max-occurs="unbounded">
                 <group-as name="props" in-json="ARRAY"/>
             </assembly>
@@ -815,6 +809,13 @@
             <index-has-key name="index-metadata-party-uuid" target=".">
                 <key-field target="@party-uuid"/>
             </index-has-key>
+            <allowed-values target="./system/@value" allow-other="yes">
+                <enum value="http://csrc.nist.gov/ns/oscal">This value identifies action types defined in the NIST OSCAL namespace.</enum>
+             </allowed-values>
+             <allowed-values target="./type[has-oscal-namespace('http://csrc.nist.gov/ns/oscal')]/@value">
+                <enum value="approval">An approval of a document instance's content.</enum>
+                <enum value="request-changes">A request from the responisble party or parties to change the content.</enum>
+            </allowed-values>
         </constraint>
     </define-assembly>