diff --git a/schema/metaschema/metaschema-module-constraints.xml b/schema/metaschema/metaschema-module-constraints.xml
index 1abeb1d3..5eb90ef8 100644
--- a/schema/metaschema/metaschema-module-constraints.xml
+++ b/schema/metaschema/metaschema-module-constraints.xml
@@ -2,7 +2,6 @@
 <metaschema-meta-constraints xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://csrc.nist.gov/ns/oscal/metaschema/1.0 ../xml/metaschema-meta-constraints.xsd">
-    <import href="metaschema-module-metaschema.xml"/>
     <context>
         <metapath target="/metaschema-meta-constraints"/>
     </context>
diff --git a/schema/metaschema/metaschema-module-metaschema.xml b/schema/metaschema/metaschema-module-metaschema.xml
index c5529dc3..10d5b11b 100644
--- a/schema/metaschema/metaschema-module-metaschema.xml
+++ b/schema/metaschema/metaschema-module-metaschema.xml
@@ -1302,13 +1302,6 @@
         <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>
             <define-assembly name="definition-context">
                 <define-flag name="name" as-type="token" required="yes"/>
                 <define-flag name="namespace" as-type="uri" required="yes"/>
diff --git a/schema/xml/metaschema-meta-constraints.xsd b/schema/xml/metaschema-meta-constraints.xsd
index 7a476a4a..287eb2e1 100644
--- a/schema/xml/metaschema-meta-constraints.xsd
+++ b/schema/xml/metaschema-meta-constraints.xsd
@@ -11,7 +11,6 @@
     <xs:element name="metaschema-meta-constraints">
         <xs:complexType>
             <xs:sequence>
-                <xs:element name="import" type="MetaschemaImportType" maxOccurs="unbounded"/>
                 <xs:element name="context" type="ModelContextType" maxOccurs="unbounded"/>
             </xs:sequence>
         </xs:complexType>
diff --git a/schema/xml/metaschema.xsd b/schema/xml/metaschema.xsd
index ab56aec2..f03086f8 100644
--- a/schema/xml/metaschema.xsd
+++ b/schema/xml/metaschema.xsd
@@ -1188,7 +1188,7 @@
   <xs:complexType name="DefineFlagConstraintsType">
     <xs:sequence>
       <xs:group ref="LetExpressionGroup"/>
-      <xs:choice maxOccurs="unbounded">
+      <xs:choice minOccurs="0" maxOccurs="unbounded">
         <xs:element minOccurs="0" name="allowed-values" type="AllowedValuesType">
           <xs:annotation>
             <xs:documentation>Constrains the allowed values for the flag.</xs:documentation>
@@ -1262,7 +1262,7 @@
   <xs:complexType name="DefineFieldConstraintsType">
     <xs:sequence>
       <xs:group ref="LetExpressionGroup"/>
-      <xs:choice minOccurs="1" maxOccurs="unbounded">
+      <xs:choice minOccurs="0" maxOccurs="unbounded">
         <xs:group ref="TargetedCommonConstraintsGroup"/>
       </xs:choice>
       <xs:element name="remarks" type="RemarksType" minOccurs="0"/>
@@ -1272,7 +1272,7 @@
   <xs:complexType name="DefineAssemblyConstraintsType">
     <xs:sequence>
       <xs:group ref="LetExpressionGroup"/>
-      <xs:choice minOccurs="1" maxOccurs="unbounded">
+      <xs:choice minOccurs="0" maxOccurs="unbounded">
         <xs:group ref="TargetedCommonConstraintsGroup"/>
         <xs:group ref="AssemblyConstraintsGroup"/>
       </xs:choice>