diff --git a/schema/metaschema/metaschema-module-constraints.xml b/schema/metaschema/metaschema-module-constraints.xml
index e5e04fc6..91346dc5 100644
--- a/schema/metaschema/metaschema-module-constraints.xml
+++ b/schema/metaschema/metaschema-module-constraints.xml
@@ -5,7 +5,7 @@
     <context>
         <metapath target="/METASCHEMA"/>
         <constraints>
-            <let var="all-imports" expression="recurse-depth('doc(resolve-uri(import/@href))/METASCHEMA')"/>
+            <let var="all-imports" expression="recurse-depth('for $import in ./import return doc(resolve-uri($import/@href))/METASCHEMA')"/>
             <index id="module-short-name-unique" target="(.|$all-imports)" name="metaschema-metadata-short-name-index">
                 <formal-name>Index Module Short Names</formal-name>
                 <description>Ensures that the current and all imported modules have a unique short name.</description>
@@ -20,18 +20,18 @@
             </expect>
             <expect id="module-top-level-root-required" level="WARNING"
               target=".[not(@abstract) or @abstract='no']"
-              test="$all-imports/define-assembly/root-name">
+              test="exists($all-imports/define-assembly/root-name)">
                 <formal-name>Require Root Assembly for Top-Level Modules</formal-name>
                 <description>A top-level module, a module that is not marked as @abstract='yes', must have at least one assembly with a root-name.</description>
                 <message>Unless marked as @abstract='yes', a Metaschema module (or an imported module) should have at least one assembly with a root-name.</message>
             </expect>
-            <is-unique id="module-namespace-unique-entry" target="namespace">
+            <is-unique id="module-namespace-unique-entry" target="namespace-binding">
                 <formal-name>Require Unique Namespace Entries</formal-name>
                 <description>Ensures that all declared namespace entries are unique.</description>
                 <key-field target="@prefix"/>
                 <key-field target="@uri"/>
             </is-unique>
-            <is-unique id="module-namespace-unique-prefix" target="namespace">
+            <is-unique id="module-namespace-unique-prefix" target="namespace-binding">
                 <formal-name>Require Unique Namespace Entry Prefixes</formal-name>
                 <description>Ensures that all declared namespace entries have a unique prefix.</description>
                 <key-field target="@prefix"/>
@@ -54,7 +54,7 @@
         <metapath target="/metaschema-module-constraints"/>
         <constraints>
             <let var="deprecated-type-map" expression="map { 'base64Binary':'base64','dateTime':'date-time','dateTime-with-timezone':'date-time-with-timezone','email':'email-address','nonNegativeInteger':'non-negative-integer','positiveInteger':'positive-integer' }"/>
-            <expect id="metaschema-deprecated-types"
+            <expect id="metaschema-deprecated-types" level="WARNING"
               target=".//matches/@datatype|.//(define-field|define-flag)/@as-type"
               test="not(.=('base64Binary','dateTime','dateTime-with-timezone','email','nonNegativeInteger','positiveInteger'))">
                 <formal-name>Avoid Deprecated Data Type Use</formal-name>
@@ -66,13 +66,13 @@
     <context>
         <metapath target="/metaschema-meta-constraints"/>
         <constraints>
-            <is-unique id="meta-constraints-namespace-unique-entry" target="namespace">
+            <is-unique id="meta-constraints-namespace-unique-entry" target="namespace-binding">
                 <formal-name>Require Unique Namespace Entries</formal-name>
                 <description>Ensures that all declared namespace entries are unique.</description>
                 <key-field target="@prefix"/>
                 <key-field target="@uri"/>
             </is-unique>
-            <is-unique id="meta-constraints-namespace-unique-prefix" target="namespace">
+            <is-unique id="meta-constraints-namespace-unique-prefix" target="namespace-binding">
                 <formal-name>Require Unique Namespace Entry Prefixes</formal-name>
                 <description>Ensures that all declared namespace entries have a unique prefix.</description>
                 <key-field target="@prefix"/>
diff --git a/schema/metaschema/metaschema-module-metaschema.xml b/schema/metaschema/metaschema-module-metaschema.xml
index 57fbec65..4bc4becc 100644
--- a/schema/metaschema/metaschema-module-metaschema.xml
+++ b/schema/metaschema/metaschema-module-metaschema.xml
@@ -1325,6 +1325,14 @@
         <description>Defines constraint rules to be applied to an existing set of Metaschema module-based models.</description>
         <root-name>metaschema-meta-constraints</root-name>
         <model>
+            <define-assembly name="import" max-occurs="unbounded">
+                <description>Declares a set of Metaschema constraints from an out-of-line resource to import, supporting composition of constraint sets.</description>
+                <group-as name="imports" in-json="ARRAY"/>
+                <define-flag name="href" as-type="uri-reference" required="yes">
+                    <description>A relative or absolute URI for retrieving an out-of-line Metaschema constraint definition.</description>
+                </define-flag>
+            </define-assembly>
+
             <assembly ref="metapath-namespace" max-occurs="unbounded">
                 <group-as name="namespace-bindings" />
             </assembly>
diff --git a/schema/metaschema/sarif-module.xml b/schema/metaschema/sarif-module.xml
index 450ca183..0bccfbe2 100644
--- a/schema/metaschema/sarif-module.xml
+++ b/schema/metaschema/sarif-module.xml
@@ -212,7 +212,7 @@
             </assembly>
         </model>
         <constraint>
-            <expect target="." test="@ruleIndex &gt;= -1">
+            <expect target="." test="@ruleIndex >= -1">
                 <message>The value '{ . }' is not greater than or equal to '-1'.</message>
             </expect>
             <!-- TODO: unique relatedLocations -->
@@ -264,7 +264,7 @@
             </define-field>
         </model>
         <constraint>
-            <expect target="." test="@id|text">
+            <expect target="." test="exists(@id|text)">
                 <message>At least one id or text must be provided.</message>
             </expect>
         </constraint>
@@ -281,7 +281,7 @@
 				<formal-name>Index</formal-name>
 				<description>The index within the run artifacts array of the artifact object associated with the artifact location.</description>
     		    <constraint>
-                    <expect target="." test="@id &gt;= -1">
+                    <expect target="." test="@id >= -1">
                         <message>The index '{ . }' is not greater than or equal to '-1'.</message>
                     </expect>
                 </constraint>
@@ -315,7 +315,7 @@
             </assembly>
         </model>
         <constraint>
-            <expect target="." test="@id &gt;= -1">
+            <expect target="." test="@id >= -1">
                 <message>The id '{ . }' is not greater than or equal to '-1'.</message>
             </expect>
             <!-- TODO: unique relatedLocations -->
@@ -344,7 +344,7 @@
             </assembly>
         </model>
         <constraint>
-            <expect target="." test="address|artifactLocation">
+            <expect target="." test="exists(address|artifactLocation)">
                 <message>At least one address or artifactLocation must be provided.</message>
             </expect>
         </constraint>
@@ -361,7 +361,7 @@
 				<formal-name>Index</formal-name>
 				<description>The index within the logical locations array.</description>
     		    <constraint>
-                    <expect target="." test="@id &gt;= -1">
+                    <expect target="." test="@id >= -1">
                         <message>The index '{ . }' is not greater than or equal to '-1'.</message>
                     </expect>
                 </constraint>
@@ -378,7 +378,7 @@
             	<formal-name>Parent Index</formal-name>
             	<description>Identifies the index of the immediate parent of the construct in which the result was detected. For example, this property might point to a logical location that represents the namespace that holds a type.</description>
             	<constraint>
-                    <expect target="." test="@id &gt;= -1">
+                    <expect target="." test="@id >= -1">
                         <message>The index '{ . }' is not greater than or equal to '-1'.</message>
                     </expect>
                 </constraint>
@@ -417,7 +417,7 @@
                 <formal-name>Character Offset</formal-name>
                 <description>The zero-based offset from the beginning of the artifact of the first character in the region.</description>
                 <constraint>
-                    <expect target="." test="@id &gt;= -1">
+                    <expect target="." test="@id >= -1">
                         <message>The offset '{ . }' is not greater than or equal to '-1'.</message>
                     </expect>
                 </constraint>
@@ -432,7 +432,7 @@
                 <formal-name>Byte Offset</formal-name>
                 <description>The zero-based offset from the beginning of the artifact of the first byte in the region</description>
                 <constraint>
-                    <expect target="." test="@id &gt;= -1">
+                    <expect target="." test="@id >= -1">
                         <message>The offset '{ . }' is not greater than or equal to '-1'.</message>
                     </expect>
                 </constraint>
@@ -449,7 +449,7 @@
             </assembly>
         </model>
         <constraint>
-            <expect target="." test="startLine|charOffset|byteOffset">
+            <expect target="." test="exists(startLine|charOffset|byteOffset)">
                 <message>At least a startLine, charOffset, or byteOffset must be provided.</message>
             </expect>
         </constraint>