diff --git a/build/ci-cd/README.md b/build/ci-cd/README.md
index 965b2d8f1e..2198764077 100644
--- a/build/ci-cd/README.md
+++ b/build/ci-cd/README.md
@@ -1,30 +1,33 @@
 # Continuous Integration and Continuous Deployment (CI/CD)
 
 This GitHub repository uses a CI/CD process that provides automation for:
+
 - Validation of contributed content and models.
 - Generation of documentation, content converters, and content in alternate formats.
 - Methods to update the [project website](https://pages.nist.gov/OSCAL).
 
 Using a CI/CD process ensures that all artifacts in [pull requests](https://github.com/usnistgov/OSCAL/blob/master/CONTRIBUTING.md) and in the [master branch](https://github.com/usnistgov/OSCAL) are valid and usable.
 
-# Provided Scripts
+## Provided Scripts
 
 The primary CircleCI supported CI/CD workflow, ```build```, is uses a series of bash scripts. The following scripts are used in this workflow for all PRs that are submitted:
 
 1. [run-all.sh](run-all.sh): Runs all of the scripts in workflow order.
-1. [validate-metaschema.sh](validate-metaschema.sh): Ensures that all [metaschema](https://github.com/usnistgov/OSCAL/tree/master/src/metaschema) are valid according to the [metaschema XML schema](https://github.com/usnistgov/metaschema/blob/master/toolchains/oscal-m2/lib/metaschema.xsd).
+1. [validate-metaschema.sh](validate-metaschema.sh): Ensures that all [metaschema](https://github.com/usnistgov/OSCAL/tree/master/src/metaschema) are valid according to the [metaschema XML schema](https://github.com/usnistgov/metaschema/blob/master/toolchains/xslt-M4/validate/metaschema.xsd).
 1. [generate-schema.sh](generate-schema.sh): Generates [XML schema](https://github.com/usnistgov/OSCAL/tree/master/xml/schema) and [JSON schema](https://github.com/usnistgov/OSCAL/tree/master/json/schema) files for each OSCAL model based on their [respective metaschemas](https://github.com/usnistgov/OSCAL/tree/master/src/metaschema).
 1. [validate-content.sh](validate-content.sh): Validates OSCAL content in the repository's [src](https://github.com/usnistgov/OSCAL/tree/master/src) against the content's respective OSCAL model and format.
 1. [generate-content-converters.sh](generate-content-converters.sh): Generates [JSON to XML](https://github.com/usnistgov/OSCAL/tree/master/xml/convert) and [XML to JSON](https://github.com/usnistgov/OSCAL/tree/master/json/convert) content conversion scripts for each OSCAL model based on their [respective metaschemas](https://github.com/usnistgov/OSCAL/tree/master/src/metaschema).
 1. [copy-and-convert-content.sh](copy-and-convert-content.sh): Copies selective content from the [src/content](https://github.com/usnistgov/OSCAL/tree/master/src/content) directory, and generates instance of this content in alternate OSCAL formats using the appropriate content converters. Note __This script requires that the process have write access to the Git repository branch that the CI/CD is operating on to work completely.__
 1. [validate-content-conversion-round-trips.sh](validate-content-conversion-round-trips.sh): Performs round trip validations of the content from XML->JSON->XML to confirm that the conversions are lossless and that resulting files comply with their schemas.
 
-Additional scripts are provided that generate content for the OSCAL project website, supported by the CircleCI ```build``` workflow on the ```master``` branch.
+    Additional scripts are provided that generate content for the OSCAL project website, supported by the CircleCI ```build``` workflow on the ```master``` branch.
+
 1. [generate-model-documentation.sh](generate-model-documentation.sh): This is used as part of the site generation pipeline to build HTML documentation for the OSCAL models.
 
-# Running the Scripts Locally
+## Running the Scripts Locally
 
 The bash scripts used in the CI/CD workflow can be run locally in the correct environment. In addition to a bash shell, to run these scripts the following must be installed:
+
 - [xmlint](http://xmlsoft.org/xmllint.html)
 - [Java](https://www.java.com/en/) 8.0 or greater
 - [Apache Maven](https://maven.apache.org/) 3.6.1 or greater
@@ -36,92 +39,90 @@ Additionally, the following packages need to be installed.
 
 NodeJS Packages:
 
-```
+```bash
 npm install -g ajv-cli
 ```
 
 Python Packages:
 
-```
+```bash
 pip install lxml
 ```
 
 The Saxon jar file needs to be retrieved. This can be two ways:
 
-1) You can set the environment variable ```SAXON_VERSION``` to the Saxon version to use. This must correspond to a valid Saxon-HE version in [Maven Central](https://search.maven.org/artifact/net.sf.saxon/Saxon-HE). Maven will be used to automatically download the Saxon-HE jar dependency.
+1. You can set the environment variable ```SAXON_VERSION``` to the Saxon version to use. This must correspond to a valid Saxon-HE version in [Maven Central](https://search.maven.org/artifact/net.sf.saxon/Saxon-HE). Maven will be used to automatically download the Saxon-HE jar dependency.
 
-For example:
+    For example:
 
-```
-export SAXON_VERSION=9.9.1-3
-```
+    ```bash
+    export SAXON_VERSION=9.9.1-3
+    ```
 
-2) You can manually download any variant of Saxon (e.g., HE, ) from [Saxonica](https://www.saxonica.com/download/java.xml) and set the ```SAXON_HOME``` environment variable to the location of the Saxon JAR.
+2. You can manually download any variant of Saxon (e.g., HE, ) from [Saxonica](https://www.saxonica.com/download/java.xml) and set the ```SAXON_HOME``` environment variable to the location of the Saxon JAR.
 
-```
+```bash
 export SAXON_HOME=~/saxon-jar-directory
 ```
 
 Finally, the Schematron Skeleton needs to be retrieved. The following commands can be used to download it.
 
-```
+```bash
 export SCHEMATRON_HOME=~/schematron-skeleton
 git clone --depth 1 --no-checkout https://github.com/Schematron/schematron.git "$SCHEMATRON_HOME"
 cd "$SCHEMATRON_HOME"
 git checkout master -- trunk/schematron/code
 ```
 
-## Further installation notes
+### Further installation notes
 
 Setting up to run in WSL (Windows subsystem for Linux) avoids many Windows-related configuration issues, but requires the entire environment be available from within the subsystem. The easiest way to accomplish this is to install the components into the subsystem directly.
 
 To check whether xmllint is installed:
 
-```
+```bash
 xmllint -version
 ```
 
 To install it
 
-```
+```bash
 sudo apt install libxml2-utils
 ```
 
 To install Java:
 
-```
+```bash
 sudo apt install openjdk-11-jre-headless
 ```
 
 To install NodeJS:
 
-```
+```bash
 sudo apt install nodejs
 ```
 
 And npm (Node package manager, separate from NodeJS):
 
-```
+```bash
 sudo apt install npm
 ```
 
-
 To install AJV (nodeJS JSON validator)
 
-```
+```bash
 npm install -g ajv-cli
 ```
 
-
 or if you want to install globally (for all users):
 
-```
+```bash
 sudo npm install -g ajv-cli
 ```
 
 Ubuntu comes with Python. To check the version:
 
-```
+```bash
 python3 -V
 ```
 
@@ -129,30 +130,28 @@ Scripts were tested with version 3.7.3 but 3.6.8 (the default in Ubuntu under WS
 
 Along with Python you also need a library, for which you need pip (a Python installer):
 
-```
+```bash
 sudo apt install python-pip
 pip install lxml
 
 ```
 
-
 To install Maven:
 
-```
+```bash
 sudo apt install maven
 ```
 
 Then run Maven to acquire Saxon:
 
-
-```
+```bash
 export SAXON_VERSION=9.9.1-3
 mvn org.apache.maven.plugins:maven-dependency-plugin:2.10:get -DartifactId=Saxon-HE -DgroupId=net.sf.saxon -Dversion=$SAXON_VERSION
 ```
 
 You will also need a copy of the ISO Schematron skeleton.
 
-```
+```bash
 mkdir $HOME/oscal-oss
 export SCHEMATRON_HOME=$HOME/oscal-oss/git-schematron
 git clone --depth 1 --no-checkout https://github.com/Schematron/schematron.git "$SCHEMATRON_HOME"
@@ -164,12 +163,12 @@ Finally, export instructions in the preceding must also be copied into .bashrc s
 
 prettyson
 
-```
+```bash
 sudo npm install -g prettyjson
 ```
 
 jq
 
-```
+```bash
 sudo apt-get install jq
 ```
diff --git a/build/metaschema b/build/metaschema
index 1b090948e9..25a56e7810 160000
--- a/build/metaschema
+++ b/build/metaschema
@@ -1 +1 @@
-Subproject commit 1b090948e9319379d4c26c9f33e2fcc46b1d2a6b
+Subproject commit 25a56e7810d3f4602ddd09c7feac528d4c6326de
diff --git a/src/metaschema/oscal_assessment-common_metaschema.xml b/src/metaschema/oscal_assessment-common_metaschema.xml
index a2be9f79e0..bff93b60b4 100644
--- a/src/metaschema/oscal_assessment-common_metaschema.xml
+++ b/src/metaschema/oscal_assessment-common_metaschema.xml
@@ -66,10 +66,10 @@
             <enum value="objective"></enum>
             <enum value="assessment"></enum>
          </allowed-values>
-         <has-cardinality target="part[@name='objective']" min-occurs="0" max-occurs="1" />
+         <has-cardinality target="part[@name='objective']" max-occurs="1" />
          <has-cardinality target="part[@name='assessment']/prop[@name='method']" min-occurs="1" max-occurs="1" />
          <has-cardinality target="part[@name='assessment']/part[@name='objects']" min-occurs="1" max-occurs="1" />
-         <has-cardinality target="part[@name='objective']/prop[@name='method-id']" min-occurs="1" max-occurs="unbounded" />
+         <has-cardinality target="part[@name='objective']/prop[@name='method-id']" min-occurs="1" />
       </constraint>
    </define-assembly>
    <define-assembly name="assessment-method">
@@ -157,7 +157,7 @@
                <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
             </model>
             <constraint>
-               <is-unique name="unique-step-responsible-role" target="responsible-role">
+               <is-unique id="unique-step-responsible-role" target="responsible-role">
                   <key-field target="@role-id"/>
                   <remarks>
                      <p>Since multiple <code>party-uuid</code> entries can be provided, each role-id must be referenced only once.</p>
@@ -190,7 +190,7 @@
             <enum value="EXAMINE">The process of reviewing, inspecting, observing, studying, or analyzing one or more assessment objects (i.e., specifications, mechanisms, or activities).</enum>
             <enum value="TEST">The process of exercising one or more assessment objects (i.e., activities or mechanisms) under specified conditions to compare actual with expected behavior.</enum>
          </allowed-values>
-         <is-unique name="unique-activity-responsible-role" target="responsible-role">
+         <is-unique id="unique-activity-responsible-role" target="responsible-role">
             <key-field target="@role-id"/>
             <remarks>
                <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -331,7 +331,7 @@
 -->               <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
             </model>
             <constraint>
-               <is-unique name="unique-associated-activity-responsible-role" target="responsible-role">
+               <is-unique id="unique-associated-activity-responsible-role" target="responsible-role">
                   <key-field target="@role-id"/>
                   <remarks>
                      <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -687,7 +687,7 @@
                      <field ref="remarks" in-xml="WITH_WRAPPER"/>
                   </model>
                   <constraint>
-                     <is-unique name="unique-ssp-uses-component-responsible-party" target="responsible-party">
+                     <is-unique id="unique-ssp-uses-component-responsible-party" target="responsible-party">
                         <key-field target="@role-id"/>
                         <remarks>
                            <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -700,7 +700,7 @@
          </define-assembly>
       </model>
       <constraint>
-         <is-unique name="unique-ssp-assessment-assets-component" target="component">
+         <is-unique id="unique-ssp-assessment-assets-component" target="component">
             <key-field target="@uuid"/>
             <remarks>
                <p>Since multiple assessment <code>component</code> entries can be provided, each component must have a unique <code>uuid</code>.</p>
@@ -887,18 +887,18 @@
          </define-field>
          <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
       </model>
-      <constraint>
-         <!-- TODO: review these and figure out where these go -->
-<!--         <allowed-values target="origin/@type" allow-other="no">
-            <!-\- CHANGED: "tool" to "******" -\->
+<!--      <constraint>
+         <!-\- TODO: review these and figure out where these go -\->
+         <allowed-values target="origin/@type" allow-other="no">
+            <!-\\- CHANGED: "tool" to "******" -\\->
             <enum value="tool">An assessment tool, defined in the assets section of the assessment plan or results.</enum>
             <enum value="test-method">A test method defined in the assessment-activities section of the assessment plan or results.</enum>
             <enum value="task">A task defined in the schedule of the assessment plan or results.</enum>
             <enum value="included-activity">An assessment activity defined in the assessment-activities section of the assessment plan or results.</enum>
             <enum value="other">The UUID points elsewhere in the this file or an imported file.</enum>
          </allowed-values>
--->      </constraint>
-   </define-assembly>
+      </constraint>
+-->   </define-assembly>
 
    <define-assembly name="origin">
       <formal-name>Origin</formal-name>
@@ -994,7 +994,7 @@
          <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
       </model>
       <constraint>
-         <is-unique name="unique-ssp-related-task-responsible-party" target="responsible-party">
+         <is-unique id="unique-ssp-related-task-responsible-party" target="responsible-party">
             <key-field target="@role-id"/>
             <remarks>
                <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -1194,7 +1194,7 @@
                      <allowed-values target="prop/@name" allow-other="yes">
                         <enum value="type">The type of remediation tracking entry. Can be multi-valued.</enum>
                      </allowed-values>
-                     <allowed-values target="prop/[@name='type']/@value" allow-other="yes">
+                     <allowed-values target="prop[@name='type']/@value" allow-other="yes">
                         <enum value="vendor-check-in">Contacted vendor to determine the status of a pending fix to a known vulnerability.</enum>
                         <enum value="status-update">Information related to the current state of response to this risk.</enum>
                         <enum value="milestone-complete">A significant step in the response plan has been achieved.</enum>
@@ -1587,12 +1587,6 @@
                </assembly>
                <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
             </model>
-            <constraint>
-               <allowed-values target="origin/@type" allow-other="no">
-                  <enum value="party">The UUID of the person or organization who made the recommendation</enum>
-                  <enum value="tool">The UUID of the tool that made the recommendation</enum>
-               </allowed-values>
-            </constraint>
          </define-assembly>
          <assembly ref="task" min-occurs="0" max-occurs="unbounded">
             <group-as name="tasks" in-json="ARRAY"/>
diff --git a/src/metaschema/oscal_assessment-plan_metaschema.xml b/src/metaschema/oscal_assessment-plan_metaschema.xml
index 13a5ff80b1..9bef67975c 100644
--- a/src/metaschema/oscal_assessment-plan_metaschema.xml
+++ b/src/metaschema/oscal_assessment-plan_metaschema.xml
@@ -67,13 +67,13 @@
                     <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
                 </model>
                 <constraint>
-                    <is-unique name="unique-ap-local-definitions-component" target="component">
+                    <is-unique id="unique-ap-local-definitions-component" target="component">
                         <key-field target="@uuid"/>
                         <remarks>
                             <p>Since multiple <code>component</code> entries can be provided, each component must have a unique <code>uuid</code>.</p>
                         </remarks>
                     </is-unique>
-                    <is-unique name="unique-ap-local-definitions-user" target="user">
+                    <is-unique id="unique-ap-local-definitions-user" target="user">
                         <key-field target="@uuid"/>
                         <remarks>
                             <p>A given <code>uuid</code> must be assigned only once to a user.</p>
diff --git a/src/metaschema/oscal_assessment-results_metaschema.xml b/src/metaschema/oscal_assessment-results_metaschema.xml
index 10fa3cab36..ebb24f1b5c 100644
--- a/src/metaschema/oscal_assessment-results_metaschema.xml
+++ b/src/metaschema/oscal_assessment-results_metaschema.xml
@@ -141,13 +141,13 @@
           </assembly>
         </model>
         <constraint>
-          <is-unique name="unique-ar-local-definitions-component" target="component">
+          <is-unique id="unique-ar-local-definitions-component" target="component">
             <key-field target="@uuid"/>
             <remarks>
               <p>Since multiple <code>component</code> entries can be provided, each component must have a unique <code>uuid</code>.</p>
             </remarks>
           </is-unique>
-          <is-unique name="unique-ar-local-definitions-user" target="user">
+          <is-unique id="unique-ar-local-definitions-user" target="user">
             <key-field target="@uuid"/>
             <remarks>
               <p>A given <code>uuid</code> must be assigned only once to a user.</p>
@@ -179,7 +179,7 @@
           </assembly>
         </model>
         <constraint>
-          <is-unique name="unique-ar-attestation-responsible-party" target="responsible-party">
+          <is-unique id="unique-ar-attestation-responsible-party" target="responsible-party">
             <key-field target="@role-id"/>
             <remarks>
               <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
diff --git a/src/metaschema/oscal_catalog_metaschema.xml b/src/metaschema/oscal_catalog_metaschema.xml
index c40f334116..92385a917a 100644
--- a/src/metaschema/oscal_catalog_metaschema.xml
+++ b/src/metaschema/oscal_catalog_metaschema.xml
@@ -45,9 +45,6 @@
                         </remarks>
                   </assembly>
             </model>
-            <constraint>
-
-            </constraint>
             <remarks>
                   <p>Catalogs may use one or more <code>group</code> objects to subdivide the control contents of a catalog.</p>
                   <p>An OSCAL catalog model provides a structured representation of control information.</p>
diff --git a/src/metaschema/oscal_complete_metaschema.xml b/src/metaschema/oscal_complete_metaschema.xml
index 82989c7ff9..f8e91c0266 100644
--- a/src/metaschema/oscal_complete_metaschema.xml
+++ b/src/metaschema/oscal_complete_metaschema.xml
@@ -3,7 +3,7 @@
 <!-- OSCAL GRAND UNIFIED MEGALOMETASCHEMA -->
 <!-- validate with XSD and Schematron (linked) -->
 <!DOCTYPE METASCHEMA [
-   <!ENTITY allowed-values-control-group-property-name SYSTEM "shared-constraints/allowed-values-control-group-property-name.ent">
+   <!ENTITY allowed-values-control-group-property-name SYSTEM "./shared-constraints/allowed-values-control-group-property-name.ent">
 ]>
 <METASCHEMA xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0">
       <schema-name>OSCAL Unified Model of Models</schema-name>
diff --git a/src/metaschema/oscal_component_metaschema.xml b/src/metaschema/oscal_component_metaschema.xml
index ed1880ef2f..7a9fe80aec 100644
--- a/src/metaschema/oscal_component_metaschema.xml
+++ b/src/metaschema/oscal_component_metaschema.xml
@@ -1,15 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <?xml-model href="../../build/metaschema/toolchains/xslt-M4/validate/metaschema-check.sch" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
 <!DOCTYPE METASCHEMA [
-   <!ENTITY allowed-values-responsible-roles-operations SYSTEM "shared-constraints/allowed-values-responsible-roles-operations.ent">
-<!ENTITY allowed-values-responsible-roles-component-production SYSTEM "shared-constraints/allowed-values-responsible-roles-component-production.ent">
-<!ENTITY allowed-values-property-name-asset-type-values SYSTEM "shared-constraints/allowed-values-property-name-asset-type-values.ent">
-<!ENTITY allowed-values-component_component_property-name SYSTEM "shared-constraints/allowed-values-component_component_property-name.ent">
-<!ENTITY allowed-values-component_component_software SYSTEM "shared-constraints/allowed-values-component_component_software.ent">
-<!ENTITY allowed-values-component_component_service SYSTEM "shared-constraints/allowed-values-component_component_service.ent">
-<!ENTITY allowed-values-component_inventory-item_property-name SYSTEM "shared-constraints/allowed-values-component_inventory-item_property-name.ent">
-<!ENTITY allowed-values-component_component_link-rel SYSTEM "shared-constraints/allowed-values-component_component_link-rel.ent">
-<!ENTITY allowed-values-component-type SYSTEM "shared-constraints/allowed-values-component-type.ent">
+  <!ENTITY allowed-values-responsible-roles-operations SYSTEM "./shared-constraints/allowed-values-responsible-roles-operations.ent">
+  <!ENTITY allowed-values-responsible-roles-component-production SYSTEM "./shared-constraints/allowed-values-responsible-roles-component-production.ent">
+  <!ENTITY allowed-values-property-name-asset-type-values SYSTEM "./shared-constraints/allowed-values-property-name-asset-type-values.ent">
+  <!ENTITY allowed-values-component_component_property-name SYSTEM "./shared-constraints/allowed-values-component_component_property-name.ent">
+  <!ENTITY allowed-values-component_component_software SYSTEM "./shared-constraints/allowed-values-component_component_software.ent">
+  <!ENTITY allowed-values-component_component_service SYSTEM "./shared-constraints/allowed-values-component_component_service.ent">
+  <!ENTITY allowed-values-component_inventory-item_property-name SYSTEM "./shared-constraints/allowed-values-component_inventory-item_property-name.ent">
+  <!ENTITY allowed-values-component_component_link-rel SYSTEM "./shared-constraints/allowed-values-component_component_link-rel.ent">
+  <!ENTITY allowed-values-component-type SYSTEM "./shared-constraints/allowed-values-component-type.ent">
 ]>
 <METASCHEMA xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0" xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/metaschema/1.0 ../../build/metaschema/toolchains/xslt-M4/validate/metaschema.xsd">
@@ -56,7 +56,7 @@
           <p>Since multiple <code>component</code> entries can be provided, each component must have a unique <code>uuid</code>.</p>
         </remarks>
       </index>
-      <is-unique name="unique-component-definition-capability" target="capability">
+      <is-unique id="unique-component-definition-capability" target="capability">
         <key-field target="@uuid"/>
         <remarks>
           <p>A given <code>component</code> must not be referenced more than once within the same <code>capability</code>.</p>
@@ -147,7 +147,7 @@
         <enum value="uses-network">This component uses the network provided by the identified network component.</enum>
       </allowed-values>
 
-      <allowed-values target="responsible-role/@role-id|control-implementation/implemented-requirement/responsible-role/@role-id||control-implementation/implemented-requirement/statement/responsible-role/@role-id" allow-other="yes">
+      <allowed-values target="responsible-role/@role-id|control-implementation/implemented-requirement/responsible-role/@role-id|control-implementation/implemented-requirement/statement/responsible-role/@role-id" allow-other="yes">
         <!-- ========================================================================================================== -->
         <!-- = Changes to the following values need to be synced with component in the SSP and component metaschemas. = -->
         <!-- CHANGED (BJR): Done -->
@@ -164,7 +164,7 @@
       <!-- = TODO: The following was copied from implementation-common as-is and should probably be setup with  = -->
       <!-- =       shared constraints; however, the values are highly static (yes/no, internal/external). -->
       <!-- =       Can be changed later with no breaking impact. -->
-      <allowed-values target="property[@name='allows-authenticated-scan']/@value">
+      <allowed-values target="prop[@name='allows-authenticated-scan']/@value">
         <enum value="yes">The component allows an authenticated scan.</enum>
         <enum value="no">The component does not allow an authenticated scan.</enum>
       </allowed-values>
@@ -211,7 +211,7 @@
             &allowed-values-component_component_service;
       </allowed-values>
 
-      <expect test="not(exists((.)[not(@type='service')]/protocol))"/>
+      <expect target="." test="not(exists((.)[not(@type='service')]/protocol))"/>
 
       <!-- ========================================================================================================== -->
       <!-- = TODO: Consider whether INTERCONNECTION constraints are appropriate here.      = -->
@@ -219,7 +219,7 @@
       <!-- =       If interconnection is not appropriate for component-defintion, we'll need different = -->
       <!-- =           component-type lists for the two models.                                        = -->
       <!-- ========================================================================================================== -->
-      <is-unique name="unique-defined-component-responsible-role" target="responsible-role">
+      <is-unique id="unique-defined-component-responsible-role" target="responsible-role">
         <key-field target="@role-id"/>
         <remarks>
           <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -275,7 +275,7 @@
       <field ref="remarks" in-xml="WITH_WRAPPER"/>
     </model>
     <constraint>
-      <is-unique name="unique-component-definition-capability-incorporates-component" target="incorporates-component">
+      <is-unique id="unique-component-definition-capability-incorporates-component" target="incorporates-component">
         <key-field target="@component-uuid"></key-field>
         <remarks>
           <p>A given <code>component</code> must not be referenced more than once within the same <code>capability</code>.</p>
@@ -330,7 +330,7 @@
       </assembly>
     </model>
     <constraint>
-      <is-unique name="unique-component-definition-control-implementation-set-parameter" target="set-parameter">
+      <is-unique id="unique-component-definition-control-implementation-set-parameter" target="set-parameter">
         <key-field target="@param-id"/>
         <remarks>
           <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
@@ -372,19 +372,19 @@
       <field ref="remarks" in-xml="WITH_WRAPPER"/>
     </model>
     <constraint>
-      <is-unique name="unique-component-definition-implemented-requirement-set-parameter" target="set-parameter">
+      <is-unique id="unique-component-definition-implemented-requirement-set-parameter" target="set-parameter">
         <key-field target="@param-id"/>
         <remarks>
           <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
         </remarks>
       </is-unique>
-      <is-unique name="unique-component-definition-implemented-requirement-responsible-role" target="responsible-role">
+      <is-unique id="unique-component-definition-implemented-requirement-responsible-role" target="responsible-role">
         <key-field target="@role-id"/>
         <remarks>
           <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
         </remarks>
       </is-unique>
-      <is-unique name="unique-component-definition-implemented-requirement-statement" target="statement">
+      <is-unique id="unique-component-definition-implemented-requirement-statement" target="statement">
         <key-field target="@statement-id"/>
         <remarks>
           <p>Since <code>statement</code> entries can be referenced using the statement's statement-id, each statement must be referenced only once.</p>
@@ -421,7 +421,7 @@
       <field ref="remarks" in-xml="WITH_WRAPPER"/>
     </model>
     <constraint>
-      <is-unique name="unique-component-definition-statement-responsible-role" target="responsible-role">
+      <is-unique id="unique-component-definition-statement-responsible-role" target="responsible-role">
         <key-field target="@role-id"/>
         <remarks>
           <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
diff --git a/src/metaschema/oscal_control-common_metaschema.xml b/src/metaschema/oscal_control-common_metaschema.xml
index 373fb83473..29e616be61 100644
--- a/src/metaschema/oscal_control-common_metaschema.xml
+++ b/src/metaschema/oscal_control-common_metaschema.xml
@@ -3,7 +3,7 @@
 <!-- OSCAL CATALOG METASCHEMA -->
 <!-- validate with XSD and Schematron (linked) -->
 <!DOCTYPE METASCHEMA [
-   <!ENTITY allowed-values-control-group-property-name SYSTEM "shared-constraints/allowed-values-control-group-property-name.ent">
+   <!ENTITY allowed-values-control-group-property-name SYSTEM "./shared-constraints/allowed-values-control-group-property-name.ent">
 ]>
 <METASCHEMA xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0" xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/metaschema/1.0 ../../build/metaschema/toolchains/xslt-M4/validate/metaschema.xsd" abstract="yes">
diff --git a/src/metaschema/oscal_implementation-common_metaschema.xml b/src/metaschema/oscal_implementation-common_metaschema.xml
index a6dd0b6bf7..6829307fef 100644
--- a/src/metaschema/oscal_implementation-common_metaschema.xml
+++ b/src/metaschema/oscal_implementation-common_metaschema.xml
@@ -1,15 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <?xml-model href="../../build/metaschema/toolchains/xslt-M4/validate/metaschema-check.sch" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
 <!DOCTYPE METASCHEMA [
-      <!ENTITY allowed-values-responsible-roles-operations SYSTEM "shared-constraints/allowed-values-responsible-roles-operations.ent">
-      <!ENTITY allowed-values-responsible-roles-component-production SYSTEM "shared-constraints/allowed-values-responsible-roles-component-production.ent">
-      <!ENTITY allowed-values-property-name-asset-type-values SYSTEM "shared-constraints/allowed-values-property-name-asset-type-values.ent">
-      <!ENTITY allowed-values-component_component_property-name SYSTEM "shared-constraints/allowed-values-component_component_property-name.ent">
-      <!ENTITY allowed-values-component_component_software SYSTEM "shared-constraints/allowed-values-component_component_software.ent">
-      <!ENTITY allowed-values-component_component_service SYSTEM "shared-constraints/allowed-values-component_component_service.ent">
-      <!ENTITY allowed-values-component_inventory-item_property-name SYSTEM "shared-constraints/allowed-values-component_inventory-item_property-name.ent">
-      <!ENTITY allowed-values-component_component_link-rel SYSTEM "shared-constraints/allowed-values-component_component_link-rel.ent">
-      <!ENTITY allowed-values-component-type SYSTEM "shared-constraints/allowed-values-component-type.ent">
+      <!ENTITY allowed-values-responsible-roles-operations SYSTEM "./shared-constraints/allowed-values-responsible-roles-operations.ent">
+      <!ENTITY allowed-values-responsible-roles-component-production SYSTEM "./shared-constraints/allowed-values-responsible-roles-component-production.ent">
+      <!ENTITY allowed-values-property-name-asset-type-values SYSTEM "./shared-constraints/allowed-values-property-name-asset-type-values.ent">
+      <!ENTITY allowed-values-component_component_property-name SYSTEM "./shared-constraints/allowed-values-component_component_property-name.ent">
+      <!ENTITY allowed-values-component_component_software SYSTEM "./shared-constraints/allowed-values-component_component_software.ent">
+      <!ENTITY allowed-values-component_component_service SYSTEM "./shared-constraints/allowed-values-component_component_service.ent">
+      <!ENTITY allowed-values-component_inventory-item_property-name SYSTEM "./shared-constraints/allowed-values-component_inventory-item_property-name.ent">
+      <!ENTITY allowed-values-component_component_link-rel SYSTEM "./shared-constraints/allowed-values-component_component_link-rel.ent">
+      <!ENTITY allowed-values-component-type SYSTEM "./shared-constraints/allowed-values-component-type.ent">
 ]>
 <METASCHEMA xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0" xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/metaschema/1.0 ../../build/metaschema/toolchains/xslt-M4/validate/metaschema.xsd" abstract="yes">
@@ -181,7 +181,7 @@
             &allowed-values-component_component_service;
                   </allowed-values>
 
-                  <expect test="not(exists((.)[not(@type='service')]/protocol))"/>
+                  <expect target="." test="not(exists((.)[not(@type='service')]/protocol))"/>
 
                   <!-- ========================================================================================================== -->
                   <!-- = INTERCONNECTION: type='interconnection' constraints                        = -->
@@ -194,7 +194,7 @@
                         <enum value="ipv6-address">An Internet Protocol Version 6 interconnection address</enum>
                         <enum value="direction">An Internet Protocol Version 6 interconnection address</enum>
                   </allowed-values>
-                  <allowed-values target="prop[(@name=('ipv4-address','ipv6-address')]/@class" allow-other="yes">
+                  <allowed-values target="prop[@name=('ipv4-address','ipv6-address')]/@class" allow-other="yes">
                         <enum value="local">The identified IP address is for this system.</enum>
                         <enum value="remote">The identified IP address is for the remote system to which this system is connected.</enum>
                   </allowed-values>
@@ -211,11 +211,11 @@
                   <matches target="prop[@name='isa-date']/@value" datatype="dateTime"/>
                   <matches target="prop[@name='ipv4-address']/@value" datatype="ip-v4-address" />
                   <matches target="prop[@name='ipv6-address']/@value" datatype="ip-v6-address" />
-                  <allowed-values target="prop[@name='direction')]/@value" allow-other="yes">
+                  <allowed-values target="prop[@name='direction']/@value" allow-other="yes">
                         <enum value="incoming">Data from the remote system flows into this system.</enum>
                         <enum value="outgoing">Data from this system flows to the remote system.</enum>
                   </allowed-values>
-                  <is-unique name="unique-system-component-responsible-role" target="responsible-role">
+                  <is-unique id="unique-system-component-responsible-role" target="responsible-role">
                         <key-field target="@role-id"/>
                         <remarks>
                               <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -238,7 +238,7 @@
                   <allowed-values allow-other="yes">
                         <enum value="this-system">The system as a whole.</enum>
                         <enum value="system">An external system, which may be a leveraged system or the other side of an interconnection.</enum>
-            &allowed-values-component-type;
+                        &allowed-values-component-type;
                         <enum value="network">A physical or virtual network.</enum>
                   </allowed-values>
             </constraint>
@@ -510,7 +510,7 @@
 
                               <!-- TODO: constrain party-id references to parties defined in the document. (BJR Unsure how to do this. )-->
 
-                              <is-unique name="unique-implemented-component-responsible-party" target="responsible-party">
+                              <is-unique id="unique-implemented-component-responsible-party" target="responsible-party">
                                     <key-field target="@role-id"/>
                                     <remarks>
                                           <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -581,9 +581,9 @@
                         <key-field target="@role-id"></key-field>
                   </index-has-key>
                   <index-has-key name="index-metadata-party-uuid" target="responsible-party">
-                        <key-field target="@party-uuid"></key-field>
+                        <key-field target="party-uuid"></key-field>
                   </index-has-key>
-                  <is-unique name="unique-inventory-item-responsible-party" target="responsible-party">
+                  <is-unique id="unique-inventory-item-responsible-party" target="responsible-party">
                         <key-field target="@role-id"/>
                         <remarks>
                               <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
diff --git a/src/metaschema/oscal_metadata_metaschema.xml b/src/metaschema/oscal_metadata_metaschema.xml
index f306a51b58..7ae1c7acbd 100644
--- a/src/metaschema/oscal_metadata_metaschema.xml
+++ b/src/metaschema/oscal_metadata_metaschema.xml
@@ -58,21 +58,21 @@
             <index id="index-metadata-roles" name="index-metadata-role-ids" target="role">
                 <key-field target="@id"/>
             </index>
-            <is-unique id="unique-metadata-doc-id" name="unique-metadata-doc-id" target="document-id">
+            <is-unique id="unique-metadata-doc-id" target="document-id">
                 <!--  CHANGE: Fixing field name @type -> @scheme   -->
                 <key-field target="@scheme"/>
-                <key-field target="value()"/>
+                <key-field target="."/>
             </is-unique>
-            <is-unique id="unique-metadata-property" name="unique-metadata-property" target="prop">
+            <is-unique id="unique-metadata-property" target="prop">
                 <key-field target="@name"/>
                 <key-field target="@ns"/>
                 <key-field target="@class"/>
                 <key-field target="@value"/>
             </is-unique>
-            <index id="index-metadata-property-id" name="index-metadata-property-id" target=".//prop">
-                <key-field target="@id"/>
+            <index id="index-metadata-property-uuid" name="index-metadata-property-uuid" target=".//prop">
+                <key-field target="@uuid"/>
             </index>
-            <is-unique id="unique-metadata-link" name="unique-metadata-link" target="link">
+            <is-unique id="unique-metadata-link" target="link">
                 <key-field target="@href"/>
                 <key-field target="@rel"/>
                 <key-field target="@media-type"/>
@@ -94,7 +94,7 @@
             <index id="index-metadata-party-organizations-uuid" name="index-metadata-party-organizations-uuid" target="party[@type='organization']">
                 <key-field target="@uuid"/>
             </index>
-            <is-unique name="unique-metadata-responsible-party" target="responsible-party">
+            <is-unique id="unique-metadata-responsible-party" target="responsible-party">
                 <key-field target="@role-id"/>
                 <remarks>
                     <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -214,9 +214,9 @@
         </description>
         <constraint>
             <!-- TODO: Dave to resolve syntax error. Likely requires updated metaschema schema -->
-            <index-has-key name="index-metadata-location-uuid" target=".">
+            <index-has-key name="index-metadata-location-uuid">
                 <!-- TODO: This is impacted by cross-document cross-references We need to relocate or localize this constraint. -->
-                <key-field target="value()"/>
+                <key-field target="."/>
             </index-has-key>
         </constraint>
     </define-flag>
@@ -228,7 +228,7 @@
         <constraint>
             <index-has-key name="index-metadata-location-uuid" target=".">
                 <!-- TODO: This is impacted by cross-document cross-references We need to relocate or localize this constraint. -->
-                <key-field target="value()"/>
+                <key-field target="."/>
             </index-has-key>
         </constraint>
     </define-field>
@@ -312,7 +312,7 @@
                 <group-as name="member-of-organizations" in-json="ARRAY"/>
                 <constraint>
                     <index-has-key name="index-metadata-party-organizations-uuid" target=".">
-                        <key-field target="value()"/>
+                        <key-field target="."/>
                     </index-has-key>
                 </constraint>
                 <remarks>
@@ -338,7 +338,7 @@
         <constraint>
             <index-has-key name="index-metadata-party-uuid" target=".">
                 <!-- TODO: This is impacted by cross-document cross-references We need to relocate or localize this constraint. -->
-                <key-field target="value()"/>
+                <key-field target="."/>
             </index-has-key>
         </constraint>
     </define-field>
@@ -387,7 +387,7 @@
         <constraint>
             <index-has-key name="index-metadata-role-id" target=".">
                 <!-- TODO: This is impacted by cross-document cross-references We need to relocate or localize this constraint. -->
-                <key-field target="value()"/>
+                <key-field target="."/>
             </index-has-key>
         </constraint>
     </define-field>
@@ -528,13 +528,13 @@
                         <enum value="agreement">Indicates the resource is a formal agreement between two or more parties.</enum>
                     </allowed-values>
                     <has-cardinality target="rlink|base64" min-occurs="1"/>
-                    <is-unique name="unique-resource-rlink-href" target="rlink">
+                    <is-unique id="unique-resource-rlink-href" target="rlink">
                         <key-field target="@href"/>
                         <remarks>
                             <p>Ensures that each rlink item references a unique resource.</p>
                         </remarks>
                     </is-unique>
-                    <is-unique name="unique-resource-base64-filename" target="base64">
+                    <is-unique id="unique-resource-base64-filename" target="base64">
                         <key-field target="@filename"/>
                         <remarks>
                             <p>Ensures that all base64 resources have a unique <code>filename</code>.
@@ -733,7 +733,7 @@
                 <key-field target="@role-id"/>
             </index-has-key>
             <index-has-key name="index-metadata-party-uuid" target="party-uuid">
-                <key-field target="value()"/>
+                <key-field target="."/>
             </index-has-key>
         </constraint>
     </define-assembly>
diff --git a/src/metaschema/oscal_poam_metaschema.xml b/src/metaschema/oscal_poam_metaschema.xml
index 8b899625de..bce14bc6be 100644
--- a/src/metaschema/oscal_poam_metaschema.xml
+++ b/src/metaschema/oscal_poam_metaschema.xml
@@ -74,7 +74,7 @@
             <field ref="remarks" in-xml="WITH_WRAPPER" min-occurs="0" max-occurs="1"/>
         </model>
         <constraint>
-            <is-unique name="unique-poam-local-definitions-component" target="component">
+            <is-unique id="unique-poam-local-definitions-component" target="component">
                 <key-field target="@uuid"/>
                 <remarks>
                     <p>Since multiple <code>component</code> entries can be provided, each component must have a unique <code>uuid</code>.</p>
diff --git a/src/metaschema/oscal_profile_metaschema.xml b/src/metaschema/oscal_profile_metaschema.xml
index 2066fb9ff0..a573ee5ef5 100644
--- a/src/metaschema/oscal_profile_metaschema.xml
+++ b/src/metaschema/oscal_profile_metaschema.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <?xml-model href="../../build/metaschema/toolchains/xslt-M4/validate/metaschema-check.sch" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
 <!DOCTYPE METASCHEMA [
-   <!ENTITY allowed-values-control-group-property-name SYSTEM "shared-constraints/allowed-values-control-group-property-name.ent">
+   <!ENTITY allowed-values-control-group-property-name SYSTEM "./shared-constraints/allowed-values-control-group-property-name.ent">
 ]>
 <METASCHEMA xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0" xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/metaschema/1.0 ../../build/metaschema/toolchains/xslt-M4/validate/metaschema.xsd">
@@ -246,19 +246,20 @@
                                     </assembly>
                               </choice>
                         </model>
-                        <constraint>
-                              <is-unique name="unique-profile-modify-set-parameter" target="set-parameter">
-                                    <key-field target="@param-id"/>
-                                    <remarks>
-                                          <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
-                                    </remarks>
-                              </is-unique>
-                        </constraint>
                   </define-assembly>
                   <assembly ref="alter" max-occurs="unbounded">
                         <group-as name="alters" in-json="ARRAY"/>
                   </assembly>
             </model>
+            <constraint>
+                  <is-unique id="unique-profile-modify-set-parameter" target="set-parameter">
+                        <key-field target="@param-id"/>
+                        <remarks>
+                              <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
+                        </remarks>
+                  </is-unique>
+            </constraint>
+            
       </define-assembly>
       <define-assembly name="insert-controls">
             <formal-name>Select controls</formal-name>
diff --git a/src/metaschema/oscal_ssp_metaschema.xml b/src/metaschema/oscal_ssp_metaschema.xml
index 6d8266b478..295356ec2e 100644
--- a/src/metaschema/oscal_ssp_metaschema.xml
+++ b/src/metaschema/oscal_ssp_metaschema.xml
@@ -6,9 +6,9 @@
 <!-- OSCAL Implementation Layer: System Security Plan (SSP) METASCHEMA -->
 <!-- validate with XSD and Schematron (linked) -->
 <!DOCTYPE METASCHEMA [
-  <!ENTITY allowed-values-responsible-roles-system SYSTEM "shared-constraints/allowed-values-responsible-roles-system.ent">
-  <!ENTITY allowed-values-responsible-roles-operations SYSTEM "shared-constraints/allowed-values-responsible-roles-operations.ent">
-  <!ENTITY allowed-values-responsible-roles-component-production SYSTEM "shared-constraints/allowed-values-responsible-roles-component-production.ent">
+  <!ENTITY allowed-values-responsible-roles-system SYSTEM "./shared-constraints/allowed-values-responsible-roles-system.ent">
+  <!ENTITY allowed-values-responsible-roles-operations SYSTEM "./shared-constraints/allowed-values-responsible-roles-operations.ent">
+  <!ENTITY allowed-values-responsible-roles-component-production SYSTEM "./shared-constraints/allowed-values-responsible-roles-component-production.ent">
 ]>
 <METASCHEMA xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0" xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/metaschema/1.0 ../../build/metaschema/toolchains/xslt-M4/validate/metaschema.xsd">
@@ -126,7 +126,7 @@
         <enum value="federation-assurance-level">A value of 1, 2, or 3 as defined by <a href="https://doi.org/10.6028/NIST.SP.800-63-3">SP 800-63-3</a>.
         </enum>
       </allowed-values>
-      <allowed-values target="prop[@name=('identity-assurance-level','authenticator-assurance-level','federation-assurance-level')]/value()">
+      <allowed-values target="prop[@name=('identity-assurance-level','authenticator-assurance-level','federation-assurance-level')]/@value">
         <enum value="1">As defined by <a href="https://doi.org/10.6028/NIST.SP.800-63-3">SP 800-63-3</a>.
         </enum>
         <enum value="2">As defined by <a href="https://doi.org/10.6028/NIST.SP.800-63-3">SP 800-63-3</a>.
@@ -134,11 +134,11 @@
         <enum value="3">As defined by <a href="https://doi.org/10.6028/NIST.SP.800-63-3">SP 800-63-3</a>.
         </enum>
       </allowed-values>
-      <allowed-values target="property/@name" allow-other="yes">
+      <allowed-values target="prop/@name" allow-other="yes">
         <enum value="cloud-deployment-model">The associated value is one of: public-cloud, private-cloud, community-cloud, government-only-cloud, hybrid-cloud, or other.</enum>
         <enum value="cloud-service-model">The associated value is one of: saas, paas, iaas, or other.</enum>
       </allowed-values>
-      <allowed-values target="prop[@name='cloud-deployment-model']/value()">
+      <allowed-values target="prop[@name='cloud-deployment-model']/@value">
         <enum value="public-cloud">The public cloud deployment model as defined by <a href="https://doi.org/10.6028/NIST.SP.800-145">The NIST Definition of Cloud Computing</a>.
         </enum>
         <enum value="private-cloud">The private cloud deployment model as defined by <a href="https://doi.org/10.6028/NIST.SP.800-145">The NIST Definition of Cloud Computing</a>.
@@ -152,7 +152,7 @@
           <p>The hybrid cloud deployment model, as defined by <a href="https://doi.org/10.6028/NIST.SP.800-145">The NIST Definition of Cloud Computing</a>, can be supported by selecting two or more of the existing deployment models.</p>
         </remarks>
       </allowed-values>
-      <allowed-values target="prop[@name='cloud-service-model']/value()">
+      <allowed-values target="prop[@name='cloud-service-model']/@value">
         <enum value="saas">Software as a service (SaaS) cloud service model as defined by <a href="https://doi.org/10.6028/NIST.SP.800-145">The NIST Definition of Cloud Computing</a>.
         </enum>
         <enum value="paas">Platform as a service (PaaS) cloud service model as defined by <a href="https://doi.org/10.6028/NIST.SP.800-145">The NIST Definition of Cloud Computing</a>.
@@ -161,7 +161,7 @@
         </enum>
         <enum value="other">Any other type of cloud service model that is exclusive to the other choices.</enum>
       </allowed-values>
-      <is-unique name="unique-ssp-system-characteristics-responsible-party" target="responsible-party">
+      <is-unique id="unique-ssp-system-characteristics-responsible-party" target="responsible-party">
         <key-field target="@role-id"/>
         <remarks>
           <p>Since <code>responsible-party</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -284,7 +284,7 @@
       <allowed-values target="prop/@name" allow-other="yes">
         <enum value="privacy-designation">Is this a privacy sensitive system? yes or no</enum>
       </allowed-values>
-      <allowed-values target="prop[@name='privacy-designation']/value()">
+      <allowed-values target="prop[@name='privacy-designation']/@value">
         <enum value="yes">The system is privacy sensitive.</enum>
         <enum value="no">The system isnot privacy sensitive.</enum>
       </allowed-values>
@@ -292,11 +292,11 @@
         <enum value="privacy-impact-assessment">A link to the privacy impact assessment.</enum>
       </allowed-values>
       <matches target="link[@rel='privacy-impact-assessment']/@href[starts-with(.,'#')]" datatype="uri-reference"/>
-      <index-has-key name="index-back-matter-resource" target="link[@rel='privacy-impact-assessment' and [starts-with(@href,'#')]]">
+      <index-has-key name="index-back-matter-resource" target="link[@rel='privacy-impact-assessment' and starts-with(@href,'#')]">
         <key-field target="@href" pattern="#(.*)"/>
       </index-has-key>
       <matches target="link[@rel='privacy-impact-assessment']/@href[not(starts-with(.,'#'))]" datatype="uri"/>
-      <allowed-values target="security-sensitivity-level|security-impact-level/(security-objective-confidentiality|security-objective-integrity|security-objective-availability)|system-information/information-type/(confidentiality-impact|integrity-impact|availability-impact)/(base|selected)">
+      <allowed-values target="information-type/(confidentiality-impact|integrity-impact|availability-impact)/(base|selected)">
         <enum value="fips-199-low">A 'low' sensitivity level as defined in <a href="https://doi.org/10.6028/NIST.FIPS.199">FIPS-199</a>.
         </enum>
         <enum value="fips-199-moderate">A 'moderate' sensitivity level as defined in <a href="https://doi.org/10.6028/NIST.FIPS.199">FIPS-199</a>.
@@ -396,7 +396,7 @@
       </define-field>
     </model>
     <constraint>
-      <is-unique name="unique-ssp-authorization-boundary-diagram" target="diagram">
+      <is-unique id="unique-ssp-authorization-boundary-diagram" target="diagram">
         <key-field target="@uuid"/>
         <remarks>
           <p>A given <code>uuid</code> must be assigned only once to a diagram.</p>
@@ -439,8 +439,8 @@
       <allowed-values target="link/@rel">
         <enum value="diagram">A reference to the diagram image.</enum>
       </allowed-values>
-      <matches target="link[@rel='diagramn']/@href[starts-with(.,'#')]" datatype="uri-reference"/>
-      <index-has-key name="index-back-matter-resource" target="link[@rel='diagram' and [starts-with(@href,'#')]]">
+      <matches target="link[@rel='diagram']/@href[starts-with(.,'#')]" datatype="uri-reference"/>
+      <index-has-key name="index-back-matter-resource" target="link[@rel='diagram' and starts-with(@href,'#')]">
         <key-field target="@href" pattern="#(.*)"/>
       </index-has-key>
       <matches target="link[@rel='diagram']/@href[not(starts-with(.,'#'))]" datatype="uri"/>
@@ -479,7 +479,7 @@
       <field ref="remarks" in-xml="WITH_WRAPPER"/>
     </model>
     <constraint>
-      <is-unique name="unique-ssp-network-architecture-diagram" target="diagram">
+      <is-unique id="unique-ssp-network-architecture-diagram" target="diagram">
         <key-field target="@uuid"/>
         <remarks>
           <p>A given <code>uuid</code> must be assigned only once to a diagram.</p>
@@ -509,7 +509,7 @@
       <field ref="remarks" in-xml="WITH_WRAPPER"/>
     </model>
     <constraint>
-      <is-unique name="unique-ssp-data-flow-diagram" target="diagram">
+      <is-unique id="unique-ssp-data-flow-diagram" target="diagram">
         <key-field target="@uuid"/>
         <remarks>
           <p>A given <code>uuid</code> must be assigned only once to a diagram.</p>
@@ -564,7 +564,7 @@
             <enum value="system-security-plan">A reference to the system security plan for the leveraged authorization.</enum>
           </allowed-values>
           <matches target="link[@rel='system-security-plan']/@href[starts-with(.,'#')]" datatype="uri-reference"/>
-          <index-has-key name="index-back-matter-resource" target="link[@rel='system-security-plan' and [starts-with(@href,'#')]]">
+          <index-has-key name="index-back-matter-resource" target="link[@rel='system-security-plan' and starts-with(@href,'#')]">
             <key-field target="@href" pattern="#(.*)"/>
           </index-has-key>
           <matches target="link[@rel='system-security-plan']/@href[not(starts-with(.,'#'))]" datatype="uri"/>
@@ -597,7 +597,7 @@
         <key-field target="@uuid"/>
       </index>
       <index-has-key name="index-system-implementation-leveraged-authorization-uuid" target="component/prop[@name='leveraged-authorization-uuid']">
-        <key-field target="value()"/>
+        <key-field target="@value"/>
       </index-has-key>
 
       <!-- References to components -->
@@ -642,7 +642,7 @@
 
       <!-- TODO: only allow a single "this-system" component -->
 
-      <is-unique name="unique-ssp-system-implementation-user" target="user">
+      <is-unique id="unique-ssp-system-implementation-user" target="user">
         <key-field target="@uuid"/>
         <remarks>
           <p>A given <code>uuid</code> must be assigned only once to a user.</p>
@@ -667,7 +667,7 @@
       </assembly>
     </model>
     <constraint>
-      <is-unique name="unique-ssp-control-implementation-set-parameter" target="set-parameter">
+      <is-unique id="unique-ssp-control-implementation-set-parameter" target="set-parameter">
         <key-field target="@param-id"/>
         <remarks>
           <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
@@ -727,35 +727,35 @@
             &allowed-values-responsible-roles-operations;
       </allowed-values>
       <index-has-key name="index-metadata-role-id" target="responsible-role|statement/responsible-role|.//by-component//responsible-role">
-        <key-field target="@role-id"></key-field>
+        <key-field target="@role-id"/>
       </index-has-key>
       <index-has-key name="index-metadata-party-uuid" target="responsible-role|statement/responsible-role|.//by-component//responsible-role">
-        <key-field target="@party-uuid"></key-field>
+        <key-field target="party-uuid"/>
       </index-has-key>
       <has-cardinality target=".//by-component" min-occurs="1">
         <remarks>
           <p>Since all implementation statements are defined at the by-component level (e.g., type=this-system), there must be at least one by-component.</p>
         </remarks>
       </has-cardinality>
-      <is-unique name="unique-ssp-implemented-requirement-set-parameter" target="set-parameter">
+      <is-unique id="unique-ssp-implemented-requirement-set-parameter" target="set-parameter">
         <key-field target="@param-id"/>
         <remarks>
           <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
         </remarks>
       </is-unique>
-      <is-unique name="unique-ssp-implemented-requirement-responsible-role" target="responsible-role">
+      <is-unique id="unique-ssp-implemented-requirement-responsible-role" target="responsible-role">
         <key-field target="@role-id"/>
         <remarks>
           <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
         </remarks>
       </is-unique>
-      <is-unique name="unique-ssp-implemented-requirement-statement" target="statement">
+      <is-unique id="unique-ssp-implemented-requirement-statement" target="statement">
         <key-field target="@statement-id"/>
         <remarks>
           <p>Since <code>statement</code> entries can be referenced using the statement's statement-id, each statement must be referenced only once.</p>
         </remarks>
       </is-unique>
-      <is-unique name="unique-ssp-implemented-requirement-by-component" target="by-component">
+      <is-unique id="unique-ssp-implemented-requirement-by-component" target="by-component">
         <key-field target="@component-uuid"/>
         <remarks>
           <p>Since <code>by-component</code> can reference <code>component</code> entries using the component's uuid, each component must be referenced only once. This ensures that all implementation statements are contained in the same <code>by-component</code> entry.</p>
@@ -794,13 +794,13 @@
       <allowed-values target="responsible-role/@role-id" allow-other="yes">
             &allowed-values-responsible-roles-operations;
       </allowed-values>
-      <is-unique name="unique-ssp-statement-responsible-role" target="responsible-role">
+      <is-unique id="unique-ssp-statement-responsible-role" target="responsible-role">
         <key-field target="@role-id"/>
         <remarks>
           <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
         </remarks>
       </is-unique>
-      <is-unique name="unique-ssp-implemented-requirement-statement-by-component" target="by-component">
+      <is-unique id="unique-ssp-implemented-requirement-statement-by-component" target="by-component">
         <key-field target="@component-uuid"/>
         <remarks>
           <p>Since <code>by-component</code> can reference <code>component</code> entries using the component's uuid, each component must be referenced only once. This ensures that all implementation statements are contained in the same <code>by-component</code> entry.</p>
@@ -882,7 +882,7 @@
               <field ref="remarks" in-xml="WITH_WRAPPER"/>
             </model>
             <constraint>
-              <is-unique name="unique-provided-responsible-role" target="responsible-role">
+              <is-unique id="unique-provided-responsible-role" target="responsible-role">
                 <key-field target="@role-id"/>
                 <remarks>
                   <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -920,7 +920,7 @@
               <field ref="remarks" in-xml="WITH_WRAPPER"/>
             </model>
             <constraint>
-              <is-unique name="unique-responsibility-responsible-role" target="responsible-role">
+              <is-unique id="unique-responsibility-responsible-role" target="responsible-role">
                 <key-field target="@role-id"/>
                 <remarks>
                   <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -932,7 +932,7 @@
         </model>
         <constraint>
           <has-cardinality target="provided|responsibility" min-occurs="1"/>
-          <index name="by-component-export-provided-uuid" target="">
+          <index name="by-component-export-provided-uuid" target="provided">
             <key-field target="@uuid"/>
           </index>
           <index-has-key name="by-component-export-provided-uuid" target="responsibility">
@@ -967,7 +967,7 @@
           </assembly>
         </model>
         <constraint>
-          <is-unique name="unique-inherited-responsible-role" target="responsible-role">
+          <is-unique id="unique-inherited-responsible-role" target="responsible-role">
             <key-field target="@role-id"/>
             <remarks>
               <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -1003,7 +1003,7 @@
           <field ref="remarks" in-xml="WITH_WRAPPER"/>
         </model>
         <constraint>
-          <is-unique name="unique-satisfied-responsible-role" target="responsible-role">
+          <is-unique id="unique-satisfied-responsible-role" target="responsible-role">
             <key-field target="@role-id"/>
             <remarks>
               <p>Since <code>responsible-role</code> associates multiple <code>party-uuid</code> entries with a single <code>role-id</code>, each role-id must be referenced only once.</p>
@@ -1022,7 +1022,7 @@
             &allowed-values-responsible-roles-operations;
             &allowed-values-responsible-roles-component-production;
       </allowed-values>
-      <is-unique name="unique-ssp-by-component-set-parameter" target="set-parameter">
+      <is-unique id="unique-ssp-by-component-set-parameter" target="set-parameter">
         <key-field target="@param-id"/>
         <remarks>
           <p>Since multiple <code>set-parameter</code> entries can be provided, each parameter must be set only once.</p>
diff --git a/src/metaschema/readme.md b/src/metaschema/readme.md
index d0437c1db0..6f6de48646 100644
--- a/src/metaschema/readme.md
+++ b/src/metaschema/readme.md
@@ -10,9 +10,9 @@ OSCAL Metaschemas are used to generate other OSCAL artifacts based on the metasc
 
 Use of Metaschemas in OSCAL allow us to maintain seamless and consistent support for multiple OSCAL model formats, including XML and JSON. Content can also be kept up-to-date in multiple formats using generated content converters, and can be validated using generated schema. Adding support for new formats (e.g., YAML) can accomplished by extending the Metaschema tooling to produce schema and converters for other formats.
 
-The Metaschema syntax (an XML application) is also described and constrained with its [own schema](https://github.com/usnistgov/metaschema/blob/master/toolchains/xslt-M4/validate/metaschema.xsd), and with a [Schematron constraints set](https://github.com/usnistgov/metaschema/blob/master/toolchains/xslt-M4/validate/metaschema-check.sch). The latter is able to enforce some of the rules described below.
+The Metaschema syntax (an XML application) is also described and constrained with its [own schema](https://github.com/usnistgov/metaschema/blob/master/toolchains/xslt-M4/validate/metaschema.xsd), and with a [Schematron constraints set](https://github.com/usnistgov/metaschema/blob/master/toolchains/xslt-M4/validate/metaschema-composition-check.sch). The latter is able to enforce some of the rules described below.
 
-#### Enumerated values
+## Enumerated values
 
 Additionally, flags may be constrained to a set of known values listed in advance.
 
@@ -34,6 +34,7 @@ Within it `valid-values`, a `value` element's `@name` attribute assigns the perm
       <value name="RIPEMD-160"/>
     </valid-values> ...
 ```
+
 ## Metaschema modeling
 
 In the case of field and flag objects, the modeling constraints to be imposed by the result schemas (either XSD or JSON Schema) over the data set, can be determined on the basis of how they are described. Assembly definitions, however, permit not only flags to be assigned to assemblies of the defined type; additionally, they contain a `model` element for a *mode declaration*. This declaration names the subcomponents to be permitted (in documents valid to the target schemas) within any assembly of the type being defined.
@@ -44,13 +45,12 @@ Among these elements, no single `@named` attribute value (which refers a model c
 
 With these limitations, a model may be defined to contain any mix of fields and assemblies.
 
-* `field` refers to a field definition and permits a single occurrence of the indicated field
-* `field/@required='yes'` a field component is to be required in a model by any schema based on the metaschema
-* `assembly` refers to an assembly definition and permits a single occurrence of the indicated assembly.
-* `fields` - same as `field`, but permits the field to be repeated. In the JSON representation the multiple values are represented as any array unless `@address` is given
-* `assemblies` - same as `fields`, but for assemblies. In JSON, this construct is also presented as an array unless there is an `@address`
-* `prose` refers to a "region of prose", that is, a section of prose text of unspecified length. In XML, prose is represented in conventional fashion as (a sequence of) `<p>` and list elements (`<ul>` or `<ol>`) perhaps with inline markup (indicating further formatting). For consistency across metaschema applications, the permitted tagging will always be conformant to the same model for prose, managed to reflect (echo) a clean HTML subset. This specification also permits the markup vocabulary to be mapped to a text-based markdown syntax, suitable for use within JSON expressions of the same or similar data.
-
+- `field` refers to a field definition and permits a single occurrence of the indicated field
+- `field/@required='yes'` a field component is to be required in a model by any schema based on the metaschema
+- `assembly` refers to an assembly definition and permits a single occurrence of the indicated assembly.
+- `fields` - same as `field`, but permits the field to be repeated. In the JSON representation the multiple values are represented as any array unless `@address` is given
+- `assemblies` - same as `fields`, but for assemblies. In JSON, this construct is also presented as an array unless there is an `@address`
+- `prose` refers to a "region of prose", that is, a section of prose text of unspecified length. In XML, prose is represented in conventional fashion as (a sequence of) `<p>` and list elements (`<ul>` or `<ol>`) perhaps with inline markup (indicating further formatting). For consistency across metaschema applications, the permitted tagging will always be conformant to the same model for prose, managed to reflect (echo) a clean HTML subset. This specification also permits the markup vocabulary to be mapped to a text-based markdown syntax, suitable for use within JSON expressions of the same or similar data.
 
 ## JSON Enhancement features
 
@@ -60,20 +60,18 @@ One problem with zero-or-more cardinality as supported by `fields` and `assembli
 
 This works, but there are also occasions when a much more concise mapping may also be supported -- if the data can be ensured to follow another rule, namely that data elements (string data) can be known to be uniquely-valued. In these cases there is a different option, namely to promote a flag of a particular known (and controlled) type, to a role as "address" -- which can (incidentally) serve as a label on a JSON property, thus improving both presentation, and addressability.
 
-Accordingly, `@address` on `field` or `assemblies` indicates that their contents (components, that is each field or assembly in the series) may be addressed using the flag (attribute) of the given name. So if `address='id'`, for example, and an `id` flag is included on the field or assembly, such flag is assumed to be unique and validable as such (at least within the scope of its parent or containing structure), thus making it suitable for use as a label; consequently, in JSON, the field or assembly can be represented as a labeled property (of an object) rather than an unlabeled member of an array (of similar objects). This both reduces the data footprint and renders the data more addressable via key constructs such as identifiers.
+Accordingly, `@address` on `field` or `assemblies` indicates that their contents (components, that is each field or assembly in the series) may be addressed using the flag (attribute) of the given name. So if `address='id'`, for example, and an `id` flag is included on the field or assembly, such flag is assumed to be unique and valid as such (at least within the scope of its parent or containing structure), thus making it suitable for use as a label; consequently, in JSON, the field or assembly can be represented as a labeled property (of an object) rather than an unlabeled member of an array (of similar objects). This both reduces the data footprint and renders the data more addressable via key constructs such as identifiers.
 
 To support this, flags used as addresses should be declared as type `ID`, providing "an extra layer of protection". On the JSON side, validating the uniqueness of these values (on same-named properties across document scope) remains TBD.
 
-
-
-```
+```xml
 <define-field name="title" as="mixed"/>
 ```
 
-```
+```xml
 <title>Water (H<sub>2</sub>0)</title>
 ```
 
-```
+```xml
 "title" : "Water (H~~2~~0)"
 ```