diff --git a/test-suite/worked-examples/everything-metaschema/models-definition-map.xml b/test-suite/worked-examples/everything-metaschema/models-definition-map.xml
index e03ca98b2..0d8f21030 100644
--- a/test-suite/worked-examples/everything-metaschema/models-definition-map.xml
+++ b/test-suite/worked-examples/everything-metaschema/models-definition-map.xml
@@ -1,6 +1,7 @@
-<map xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
-     namespace="http://csrc.nist.gov/metaschema/ns/everything"
-     prefix="http://csrc.nist.gov/metaschema/ns/everything">
+<model xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+       root-at="EVERYTHING"
+       namespace="http://csrc.nist.gov/metaschema/ns/everything"
+       prefix="everything">
    <assembly scope="global" key="EVERYTHING" gi="EVERYTHING">
       <flag as-type="string" scope="global" key="id" gi="id"/>
       <field scope="global" key="field-1only" gi="field-1only">
@@ -13,23 +14,23 @@
          <flag as-type="string" scope="global" key="id" gi="id"/>
          <value as-type="string" key="CUSTOM-VALUE-KEY"/>
       </field>
-      <group key="groupable-fields" gi="groupable-fields">
+      <group key="groupable-fields">
          <field scope="global" gi="field-groupable">
             <value as-type="string" key="STRVALUE"/>
          </field>
       </group>
-      <group key="wrapped-fields" gi="wrapped-fields">
+      <group key="wrapped-fields" gi="wrapped-fields" group-json="ARRAY">
          <field scope="global" gi="field-wrappable">
             <value as-type="string" key="STRVALUE"/>
          </field>
       </group>
-      <group key="keyed-fields" gi="keyed-fields" json-key-flag="id">
+      <group key="keyed-fields" group-json="BY_KEY" json-key-flag="id">
          <field scope="global" gi="field-by-key" json-key-flag="id">
             <flag as-type="string" scope="global" key="id" gi="id"/>
             <value as-type="string" key="STRVALUE"/>
          </field>
       </group>
-      <group key="dynamic-value-key-fields" gi="dynamic-value-key-fields">
+      <group key="dynamic-value-key-fields">
          <field scope="global" gi="field-dynamic-value-key">
             <flag as-type="string" scope="global" key="id" gi="id"/>
             <value as-type="string" key-flag="id"/>
@@ -47,14 +48,14 @@
          </field>
          <assembly scope="global" key="assembly-1only" gi="assembly-1only"/>
       </assembly>
-      <group key="groupable-assemblies" gi="groupable-assemblies">
+      <group key="groupable-assemblies">
          <assembly scope="global" gi="assembly-groupable">
-            <group key="groupable-fields" gi="groupable-fields">
+            <group key="groupable-fields">
                <field scope="global" gi="field-groupable">
                   <value as-type="string" key="STRVALUE"/>
                </field>
             </group>
-            <group key="groupable-assemblies" gi="groupable-assemblies">
+            <group key="groupable-assemblies">
                <assembly scope="global" gi="assembly-groupable"/>
             </group>
          </assembly>
@@ -71,22 +72,22 @@
             </group>
          </assembly>
       </group>
-      <group key="keyed-assemblies" gi="keyed-assemblies" json-key-flag="id">
+      <group key="keyed-assemblies" group-json="BY_KEY" json-key-flag="id">
          <assembly scope="global" gi="assembly-by-key" json-key-flag="id">
             <flag as-type="string" scope="global" key="id" gi="id"/>
-            <group key="keyed-fields" gi="keyed-fields" json-key-flag="id">
+            <group key="keyed-fields" group-json="BY_KEY" json-key-flag="id">
                <field scope="global" gi="field-by-key" json-key-flag="id">
                   <flag as-type="string" scope="global" key="id" gi="id"/>
                   <value as-type="string" key="STRVALUE"/>
                </field>
             </group>
-            <group key="keyed-assemblies" gi="keyed-assemblies" json-key-flag="id">
+            <group key="keyed-assemblies" group-json="BY_KEY" json-key-flag="id">
                <assembly scope="global" gi="assembly-by-key" json-key-flag="id"/>
             </group>
          </assembly>
       </group>
-      <group key="everything-recursive" gi="everything-recursive">
+      <group key="everything-recursive">
          <assembly scope="global" gi="EVERYTHING"/>
       </group>
    </assembly>
-</map>
+</model>
diff --git a/test-suite/worked-examples/everything-metaschema/models_metaschema.xml b/test-suite/worked-examples/everything-metaschema/models_metaschema.xml
index 0c5c43a8a..25182582e 100644
--- a/test-suite/worked-examples/everything-metaschema/models_metaschema.xml
+++ b/test-suite/worked-examples/everything-metaschema/models_metaschema.xml
@@ -37,7 +37,7 @@
                 <group-as name="groupable-fields"/>
             </field>
             <field ref="field-wrappable" max-occurs="unbounded">
-                <group-as name="wrapped-fields" in-xml="GROUPED"/>
+                <group-as name="wrapped-fields" in-xml="GROUPED" in-json="ARRAY"/>
             </field>
             <field ref="field-by-key" max-occurs="unbounded">
                 <group-as name="keyed-fields" in-json="BY_KEY"/>
diff --git a/toolchains/xslt-proto-v04/compose/make-model-map.xsl b/toolchains/xslt-proto-v04/compose/make-model-map.xsl
index 2e4116f11..6d13e69a0 100644
--- a/toolchains/xslt-proto-v04/compose/make-model-map.xsl
+++ b/toolchains/xslt-proto-v04/compose/make-model-map.xsl
@@ -13,7 +13,7 @@
     
     <xsl:template match="/METASCHEMA">
         <map namespace="{child::namespace ! normalize-space(.) }"
-            prefix="{child::namespace ! normalize-space(.) }">
+            prefix="{child::short-name ! normalize-space(.) }">
             <xsl:apply-templates select="child::*[exists(root-name)]" mode="build"/>
         </map>
     </xsl:template>
diff --git a/toolchains/xslt-proto-v04/compose/reduce-map.xsl b/toolchains/xslt-proto-v04/compose/reduce-map.xsl
index bdfaff72b..83444f4c2 100644
--- a/toolchains/xslt-proto-v04/compose/reduce-map.xsl
+++ b/toolchains/xslt-proto-v04/compose/reduce-map.xsl
@@ -11,8 +11,14 @@
     
     <xsl:mode on-no-match="shallow-copy"/>
     
-    <xsl:template match="@group-name | @group-json | @group-xml | @in-xml | @link | @root-name | @use-name"/>
+    <xsl:template match="@group-name | @group-xml | @in-xml | @link | @root-name | @use-name"/>
     
+    <xsl:template match="/map">
+        <model root-at="{*/@root-name}">
+            <xsl:copy-of select="@*"/>
+            <xsl:apply-templates/>
+        </model>
+    </xsl:template>
     
     <xsl:template match="@name">
         <xsl:if test="empty(../parent::group)">
diff --git a/toolchains/xslt-proto-v04/compose/unfold-model-map.xsl b/toolchains/xslt-proto-v04/compose/unfold-model-map.xsl
index 9f92b7b04..8828f1456 100644
--- a/toolchains/xslt-proto-v04/compose/unfold-model-map.xsl
+++ b/toolchains/xslt-proto-v04/compose/unfold-model-map.xsl
@@ -11,10 +11,13 @@
     
     <xsl:mode on-no-match="shallow-copy"/>
     
+    <!-- Moved up to new 'group' parent -->
+    <xsl:template match="@group-json | @group-xml | @group-name"/>
+    
     <xsl:template match="*[exists(@group-name)]">
         <group name="{@group-name}" in-xml="{ if (@group-xml='GROUPED') then 'SHOWN' else 'HIDDEN' }"
             max-occurs="1" min-occurs="{ if (@min-occurs='0') then '0' else '1'}">
-            <xsl:copy-of select="@json-key-flag"/>
+            <xsl:copy-of select="@json-key-flag | @group-json"/>
             <xsl:next-match/>
         </group>
     </xsl:template>
diff --git a/toolchains/xslt-proto-v04/converter-gen/produce-xml-converter.xsl b/toolchains/xslt-proto-v04/converter-gen/produce-xml-converter.xsl
new file mode 100644
index 000000000..86dfa19d6
--- /dev/null
+++ b/toolchains/xslt-proto-v04/converter-gen/produce-xml-converter.xsl
@@ -0,0 +1,181 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:math="http://www.w3.org/2005/xpath-functions/math"
+    xmlns:m="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+    xmlns:XSLT="http://csrc.nist.gov/ns/oscal/metaschema/xslt-alias"
+    
+    xpath-default-namespace="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+    exclude-result-prefixes="xs math"
+    version="3.0"
+    xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel">
+    
+<!-- Purpose: Produce an XSLT for converting XML valid to a Metaschema model, to its supermodel equivalent. -->
+<!-- Input:   A Metaschema definition map -->
+<!-- Output:  An XSLT -->
+
+    <xsl:output indent="yes"/>
+    
+    <xsl:namespace-alias stylesheet-prefix="XSLT" result-prefix="xsl"/>
+    
+    <xsl:variable name="source-namespace" select="string(/*/@namespace)"/>
+    <xsl:variable name="source-prefix"    select="string(/*/@prefix)"/>
+    
+    <xsl:template match="/model">
+        <XSLT:stylesheet version="3.0" xpath-default-namespace="{ $source-namespace }"
+            exclude-result-prefixes="#all">
+
+            <XSLT:strip-space elements="{distinct-values(//assembly/@gi)}"/>
+            
+            <xsl:comment> METASCHEMA conversion stylesheet supports XML -> METASCHEMA/SUPERMODEL conversion </xsl:comment>
+            <xsl:text>&#xA;</xsl:text>
+            <xsl:comment> 888888888888888888888888888888888888888888888888888888888888888888888888888888888 </xsl:comment>
+            <xsl:text>&#xA;</xsl:text>
+
+            <!--<XSLT:character-map name="delimiters">
+                <!-\- Rewrites Unicode PUA char E0000 to reverse solidus -\->
+                <!-\-<XSLT:output-character character="&#xE0000;" string="\"/>-\->
+            </XSLT:character-map>-->
+
+            <!-- first we produce templates for (each) of the global definitions.-->
+            <xsl:for-each-group select="//*[@scope = 'global']"
+                group-by="string-join((local-name(), @gi), ':')">
+                <!-- These are all the same so we do only one -->
+                <xsl:apply-templates select="current-group()[1]" mode="make-template"/>
+            </xsl:for-each-group>
+
+            <!-- next we produce templates for local definitions -->
+            <xsl:apply-templates select=".//assembly | .//field | .//flag" mode="make-template-for-local"/>
+
+            <!--finally, a template for copying prose across, stripping ns -->
+            <XSLT:template match="*" mode="cast-prose">
+                <XSLT:element name="{{ local-name() }}" namespace="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel">
+                    <XSLT:copy-of select="@*"/>
+                    <XSLT:apply-templates mode="#current"/>     
+                </XSLT:element>
+            </XSLT:template>
+            
+        </XSLT:stylesheet> 
+    </xsl:template>
+    
+    <xsl:template match="*[@scope='global']" mode="make-template-for-local"/>
+    
+    <xsl:template match="*" mode="make-template-for-local">
+        <xsl:apply-templates select="." mode="make-template"/>
+    </xsl:template>
+ 
+    <!-- no template for implicit wrappers on markup-multiline -->
+    <xsl:template priority="2" match="field[empty(@gi)][value/@as-type='markup-multiline']" mode="make-template"/>
+        
+    <xsl:template match="*" mode="make-template">
+        <xsl:variable name="matching">
+            <xsl:apply-templates select="." mode="make-xml-match"/>
+        </xsl:variable>
+        <xsl:variable name="json-key-flag-name" select="@json-key-flag"/>
+        <XSLT:template match="{ $matching}">
+            <xsl:element name="{ local-name() }" namespace="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel">
+                <xsl:copy-of select="@* except @scope"/>
+                <xsl:if test="self::field[empty(flag[not(@key=$json-key-flag-name)])]">
+                    <xsl:attribute name="in-json">STRING</xsl:attribute>
+                </xsl:if>
+                <xsl:for-each select="parent::model" expand-text="true">
+                    <XSLT:if test=". is /*">
+                        <XSLT:attribute name="namespace">{ $source-namespace }</XSLT:attribute>
+                        <!-- don't need unless we have a requirement to prefix in serialization: <XSLT:attribute name="prefix">{ $source-prefix }</XSLT:attribute>-->
+                    </XSLT:if>
+                </xsl:for-each>
+                <xsl:apply-templates select="*" mode="make-pull"/>     
+            </xsl:element>
+        </XSLT:template>
+    </xsl:template>
+    
+    <xsl:template match="flag" mode="make-template">
+        <xsl:variable name="matching">
+            <xsl:apply-templates select="." mode="make-xml-match"/>
+        </xsl:variable>
+        <XSLT:template match="{ $matching}">
+            <flag>
+                <xsl:copy-of select="@* except @scope"/>
+                <XSLT:value-of select="."/>     
+            </flag>
+        </XSLT:template>
+    </xsl:template>
+    
+    <xsl:template priority="11" match="flag[@scope='global']" mode="make-xml-match make-xml-step">
+        <xsl:text>@</xsl:text>
+        <xsl:value-of select="@gi"/>
+    </xsl:template>
+    
+    <xsl:template priority="10" match="*[@scope='global']" mode="make-xml-match make-xml-step">
+        <xsl:value-of select="@gi"/>
+    </xsl:template>
+    
+    <xsl:template match="*" mode="make-xml-match">
+        <xsl:for-each select="ancestor-or-self::*[@gi]">
+            <xsl:value-of select="if (exists(self::flag)) then '/@' else '/'"/>
+            <xsl:apply-templates select="." mode="make-xml-step"/>
+        </xsl:for-each>
+    </xsl:template>
+
+    <xsl:template match="*" mode="make-pull">
+        <pull who="{local-name()}">
+            <xsl:copy-of select="@gi | @key"/>
+        </pull>
+    </xsl:template>
+    
+    <xsl:variable name="prose-elements">p | ul | ol | pre | h1 | h2 | h3 | h4 | h5 | h6 | table</xsl:variable>
+    
+    <!-- A field without a GI is implicit in the XML -->
+    <xsl:template priority="2" match="field[empty(@gi)][value/@as-type='markup-multiline']" mode="make-pull">
+        <XSLT:for-each-group select="{ $prose-elements }" group-by="true()">
+            <field>
+                <xsl:copy-of select="@gi | @key"/>
+                <XSLT:apply-templates select="current-group()" mode="cast-prose"/>
+            </field>
+        </XSLT:for-each-group>
+    </xsl:template>
+    
+    <xsl:template match="flag" mode="make-pull">
+        <XSLT:apply-templates select="@{@gi}"/>
+    </xsl:template>
+    
+    <xsl:template match="field | assembly | group[exists(@gi)]" mode="make-pull">
+        <XSLT:apply-templates select="{@gi}"/>
+    </xsl:template>
+    
+    <xsl:template priority="2" match="group" mode="make-pull">
+        <xsl:variable name="json-grouping" select="if (exists(@group-json)) then @group-json else 'SINGLETON_OR_ARRAY'"/>
+        <XSLT:for-each-group select="{ */@gi }" group-by="true()">
+            <group in-json="{ $json-grouping }">
+                <xsl:copy-of select="@key"/>
+                <XSLT:apply-templates select="current-group()"/>
+            </group>
+        </XSLT:for-each-group>
+    </xsl:template>
+    
+    
+    <!--<xsl:template match="field | assembly" mode="make-pull">
+        <XSLT:for-each select="{@gi}">
+            <xsl:element name="{ local-name() }"
+                namespace="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel">
+                <xsl:copy-of select="@gi | @key"/>
+                <xsl:apply-templates mode="#current"/>
+            </xsl:element>
+        </XSLT:for-each>
+    </xsl:template>-->
+    
+    <xsl:template match="value[@as-type='markup-multiline']" mode="make-pull">
+        <XSLT:for-each-group select="{ $prose-elements }" group-by="true()">
+            <XSLT:apply-templates select="current-group()" mode="cast-prose"/>
+        </XSLT:for-each-group>
+    </xsl:template>
+    
+    <xsl:template match="value" mode="make-pull">
+        <value>
+            <xsl:copy-of select="@gi | @key | @as-type"/>
+            <XSLT:value-of select="."/>
+        </value>
+    </xsl:template>
+    
+    
+</xsl:stylesheet>
\ No newline at end of file
diff --git a/toolchains/xslt-proto-v04/converter-gen/supermodel-to-json.xsl b/toolchains/xslt-proto-v04/converter-gen/supermodel-to-json.xsl
new file mode 100644
index 000000000..5a87715d3
--- /dev/null
+++ b/toolchains/xslt-proto-v04/converter-gen/supermodel-to-json.xsl
@@ -0,0 +1,115 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:math="http://www.w3.org/2005/xpath-functions/math"
+    xpath-default-namespace="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel"
+    exclude-result-prefixes="xs math"
+    version="3.0">
+    
+    <xsl:output indent="true"/>
+    <xsl:strip-space elements="*"/>
+    <xsl:preserve-space elements="flag value"/>
+    
+    <xsl:variable name="ns" select="/*/@namespace"/>
+    
+    <!--group assembly field flag value-->
+    
+    <xsl:template match="group">
+        <array>
+            <xsl:copy-of select="@key"/>
+            <xsl:apply-templates/>
+        </array>
+    </xsl:template>
+    
+    <xsl:template match="group[@in-json='BY_KEY']">
+        <map>
+            <xsl:copy-of select="@key"/>
+            <xsl:apply-templates/>
+        </map>
+    </xsl:template>
+    
+    <xsl:template match="flag[@key=../@json-key-flag]"/>
+    
+    <xsl:template match="group[@in-json='SINGLETON_OR_ARRAY'][count(*)=1]">
+        <xsl:apply-templates>
+            <xsl:with-param name="group-key" select="@key"/>
+        </xsl:apply-templates>
+    </xsl:template>
+    
+    <xsl:template priority="2" match="group/assembly | group/field">
+        <!-- $group-key is only provided when group/@in-json="SINGLETON_OR_ASSEMBLY" and there is one member of the group -->
+        <xsl:param name="group-key" select="()"/>
+        <!--@json-key-flag is only available when group/@in-json="BY_KEY"-->
+        <xsl:variable name="json-key-flag-name" select="@json-key-flag"/>
+        <map>
+            <xsl:copy-of select="($group-key,@key)[1]"/>
+            <!-- when there's a JSON key flag, we get the key from there -->
+            <xsl:for-each select="flag[@key=$json-key-flag-name]">
+                <xsl:attribute name="key" select="."/>
+            </xsl:for-each>
+            <xsl:apply-templates/>
+        </map>
+    </xsl:template>
+    
+    <xsl:template priority="3" match="group/field[@in-json='STRING']">
+        <xsl:param name="group-key" select="()"/>
+        <xsl:variable name="json-key-flag-name" select="@json-key-flag"/>
+        <!-- with no flags, this field has only its value -->
+        <xsl:apply-templates>
+                <xsl:with-param name="use-key" select="flag[@key=$json-key-flag-name]"/>
+            </xsl:apply-templates>
+    </xsl:template>
+    
+    <xsl:template match="assembly">
+        <map key="{@key}">
+            <xsl:apply-templates/>
+        </map>
+    </xsl:template>
+    
+    <xsl:template match="field">
+        <map key="{@key}">
+            <xsl:apply-templates/>
+        </map>
+    </xsl:template>
+    
+    <xsl:template match="field[@in-json='STRING']">
+        <!-- when there are no flags, the field is a string whose value is the value -->
+        <string>
+            <xsl:copy-of select="@key"/>
+            <xsl:value-of select="value"/>
+        </string>
+    </xsl:template>
+    
+    <xsl:template match="flag">
+        <string>
+            <xsl:copy-of select="@key"/>
+            <xsl:apply-templates/>
+        </string>
+    </xsl:template>
+    
+    <xsl:template match="field[@in-json='STRING']/value">
+        <xsl:param name="use-key" select="()"/>
+        <string>
+            <xsl:for-each select="$use-key">
+                <xsl:attribute name="key" select="."/>
+            </xsl:for-each>
+            <xsl:apply-templates/>
+        </string>
+    </xsl:template>
+    
+    <xsl:template match="value">
+        <xsl:param name="use-key" select="()"/>
+        <string key="{ ($use-key,@key)[1] }">
+            <xsl:apply-templates/>
+        </string>
+    </xsl:template>
+    
+    <xsl:template match="p | ul | ol | pre | h1 | h2 | h3 | h4 | h5 | h6 | table">
+        <xsl:apply-templates select="." mode="make-markdown"/>
+    </xsl:template>
+    
+    
+    
+    
+    
+</xsl:stylesheet>
\ No newline at end of file
diff --git a/toolchains/xslt-proto-v04/converter-gen/supermodel-to-xml-serializer.xsl b/toolchains/xslt-proto-v04/converter-gen/supermodel-to-xml-serializer.xsl
new file mode 100644
index 000000000..4ce2cccf7
--- /dev/null
+++ b/toolchains/xslt-proto-v04/converter-gen/supermodel-to-xml-serializer.xsl
@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:math="http://www.w3.org/2005/xpath-functions/math"
+    xpath-default-namespace="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel"
+    exclude-result-prefixes="xs math"
+    version="3.0">
+    
+    <xsl:output indent="true"/>
+    <xsl:strip-space elements="*"/>
+    <xsl:preserve-space elements="flag value"/>
+    
+    <xsl:variable name="ns" select="/*/@namespace"/>
+    
+    <xsl:template match="*[exists(@gi)]">
+        <xsl:element name="{@gi}" namespace="{ $ns }">
+            <!-- putting flags first in case of disarranged inputs -->
+            <xsl:apply-templates select="flag, (* except flag)"/>
+        </xsl:element>
+    </xsl:template>
+    
+    <xsl:template match="p | ul | ol | pre | h1 | h2 | h3 | h4 | h5 | h6 | table">
+        <xsl:apply-templates select="." mode="cast-prose"/>
+    </xsl:template>
+    
+    <xsl:template priority="2" match="flag">
+        <xsl:attribute name="{@gi}">
+            <xsl:apply-templates/>
+        </xsl:attribute>
+    </xsl:template>
+    
+    <xsl:template match="*" mode="cast-prose">
+        <xsl:element name="{local-name()}" namespace="{ $ns }">
+            <xsl:apply-templates mode="#current"/>
+        </xsl:element>
+    </xsl:template>
+    
+    
+    
+</xsl:stylesheet>
\ No newline at end of file