diff --git a/xml/constraints.rng.in b/xml/constraints.rng.in
index 5e0f8571e2..786b783d19 100644
--- a/xml/constraints.rng.in
+++ b/xml/constraints.rng.in
@@ -1,116 +1,155 @@
 <?xml version="1.0" encoding="utf-8"?>
 <grammar xmlns="http://relaxng.org/ns/structure/1.0" 
          datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
   <start>
       <ref name="element-constraints"/>
   </start>
 
   <define name="element-constraints">
       <zeroOrMore>
 	<choice>
 	  <ref name="element-location"/>
 	  <ref name="element-colocation"/>
 	  <ref name="element-order"/>
 	</choice>
       </zeroOrMore>
   </define>
 
   <define name="element-location">
     <element name="rsc_location">
       <attribute name="id"><data type="ID"/></attribute>
       <attribute name="rsc"><data type="IDREF"/></attribute>
       <choice>
 	<group>
 	  <externalRef href="score.rng"/>
 	  <attribute name="node"><data type="IDREF"/></attribute>
 	</group>
 	<oneOrMore>
 	  <externalRef href="rule-@DTD_VERSION@.rng"/>
 	</oneOrMore>
       </choice>
       <optional>
 	<ref name="element-lifetime"/>
       </optional>
     </element>
   </define>
 
-  <define name="element-colocation">
-    <element name="rsc_colocation">
+  <define name="element-resource-set">
+    <element name="resource_set">
       <attribute name="id"><data type="ID"/></attribute>
-      <attribute name="rsc"><text/></attribute>
-      <attribute name="with"><text/></attribute>
-      <!-- Ideally these would be IDREFs, but that excludes colocation with individual clones
-	   <attribute name="from"><data type="IDREF"/></attribute>
-	   <attribute name="to"><data type="IDREF"/></attribute>
-	  -->
-      <externalRef href="score.rng"/>
       <optional>
-	<ref name="element-lifetime"/>
+	<attribute name="sequential"><data type="boolean"/></attribute>
       </optional>
       <optional>
-	<attribute name="rsc-role">
-	  <ref name="attribute-roles"/>
+	<attribute name="action">
+	  <ref name="attribute-actions"/>
 	</attribute>
       </optional>
       <optional>
-	<attribute name="with-rsc-role">
+	<attribute name="role">
 	  <ref name="attribute-roles"/>
 	</attribute>
       </optional>
+      <optional>
+	<externalRef href="score.rng"/>
+      </optional>
+      <oneOrMore>
+	<element name="resource_ref">
+	  <attribute name="id"><data type="IDREF"/></attribute>
+	</element>
+      </oneOrMore>
     </element>
   </define>
 
-  <define name="element-order">
-    <element name="rsc_order">
+  <define name="element-colocation">
+    <element name="rsc_colocation">
       <attribute name="id"><data type="ID"/></attribute>
-      <attribute name="rsc"><data type="IDREF"/></attribute>
-      <attribute name="before"><data type="IDREF"/></attribute>
       <optional>
 	<externalRef href="score.rng"/>
       </optional>
       <optional>
 	<ref name="element-lifetime"/>
       </optional>
+      <choice>
+	<oneOrMore>
+	  <ref name="element-resource-set"/>
+	</oneOrMore>
+	<group>
+	  <attribute name="rsc"><data type="IDREF"/></attribute>
+	  <attribute name="with"><data type="IDREF"/></attribute>
+	  <optional>
+	    <attribute name="rsc-role">
+	      <ref name="attribute-roles"/>
+	    </attribute>
+	  </optional>
+	  <optional>
+	    <attribute name="with-rsc-role">
+	      <ref name="attribute-roles"/>
+	    </attribute>
+	  </optional>
+	</group>
+      <choice>
+    </element>
+  </define>
+
+  <define name="element-order">
+    <element name="rsc_order">
+      <attribute name="id"><data type="ID"/></attribute>
       <optional>
-	<attribute name="symmetrical"><data type="boolean"/></attribute>
-      </optional>
-      <optional>
-	<attribute name="rsc-action">
-	  <ref name="attribute-actions"/>
-	</attribute>
+	<ref name="element-lifetime"/>
       </optional>
       <optional>
-	<attribute name="before-rsc-action">
-	  <ref name="attribute-actions"/>
-	</attribute>
+	<attribute name="symmetrical"><data type="boolean"/></attribute>
       </optional>
+      <choice>
+	<oneOrMore>
+	  <ref name="element-resource-set"/>
+	</oneOrMore>
+	<group>
+	  <attribute name="rsc"><data type="IDREF"/></attribute>
+	  <attribute name="before"><data type="IDREF"/></attribute>
+	  <optional>
+	    <externalRef href="score.rng"/>
+	  </optional>
+	  <optional>
+	    <attribute name="rsc-action">
+	      <ref name="attribute-actions"/>
+	    </attribute>
+	  </optional>
+	  <optional>
+	    <attribute name="before-rsc-action">
+	      <ref name="attribute-actions"/>
+	    </attribute>
+	  </optional>
+	</group>
+      </choice>
     </element>
   </define>
  
   <define name="attribute-actions">
     <choice>
       <value>start</value>
       <value>promote</value>
       <value>demote</value>
       <value>stop</value>
     </choice>
   </define>
       
   <define name="attribute-roles">
     <choice>
       <value>Stopped</value>
       <value>Started</value>
       <value>Master</value>
       <value>Slave</value>
     </choice>
   </define>
 
   <define name="element-lifetime">
     <element name="lifetime">
       <oneOrMore>
 	<externalRef href="rule-@DTD_VERSION@.rng"/>
       </oneOrMore>
     </element>
   </define>
   
 </grammar>