-- XSD schema extracted from ITU-T Z.151 (11/2008)

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!--
== XML Schema for the User Requirements Notation (Recommendation ITU-T Z.151)
== Version: 20120112
-->
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" attributeFormDefault="unqualified" 
                                                         elementFormDefault="qualified">

  <!-- ========================== -->
  <!-- =====  Root Element  ===== -->
  <!-- ========================== -->
  <xsd:element name="URNspec" type="URNspec"/>
  <!-- ================================================== -->
  <!-- ============ Simple Type Definitions ============  -->
  <!-- ================================================== -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ComponentKind  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="ComponentKind">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Team"/>
      <xsd:enumeration value="Object"/>
      <xsd:enumeration value="Process"/>
      <xsd:enumeration value="Agent"/>
      <xsd:enumeration value="Actor"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ContributionType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="ContributionType">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Make"/>
      <xsd:enumeration value="Help"/>
      <xsd:enumeration value="SomePositive"/>
      <xsd:enumeration value="Unknown"/>
      <xsd:enumeration value="SomeNegative"/>
      <xsd:enumeration value="Hurt"/>
      <xsd:enumeration value="Break"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  DatatypeKind  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="DatatypeKind">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Boolean"/>
      <xsd:enumeration value="Integer"/>
      <xsd:enumeration value="Enumeration"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  DecompositionType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="DecompositionType">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="AND"/>
      <xsd:enumeration value="XOR"/>
      <xsd:enumeration value="IOR"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  DeviceKind  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="DeviceKind">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Processor"/>
      <xsd:enumeration value="Disk"/>
      <xsd:enumeration value="DSP"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ImportanceType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="ImportanceType">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="High"/>
      <xsd:enumeration value="Medium"/>
      <xsd:enumeration value="Low"/>
      <xsd:enumeration value="None"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  IntentionalElementType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="IntentionalElementType">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Softgoal"/>
      <xsd:enumeration value="Goal"/>
      <xsd:enumeration value="Task"/>
      <xsd:enumeration value="Resource"/>
      <xsd:enumeration value="Belief"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  QualitativeLabel  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="QualitativeLabel">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Denied"/>
      <xsd:enumeration value="WeaklyDenied"/>
      <xsd:enumeration value="WeaklySatisfied"/>
      <xsd:enumeration value="Satisfied"/>
      <xsd:enumeration value="Conflict"/>
      <xsd:enumeration value="Unknown"/>
      <xsd:enumeration value="None"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  TimeUnit  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="TimeUnit">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="year"/>
      <xsd:enumeration value="day"/>
      <xsd:enumeration value="h"/>
      <xsd:enumeration value="s"/>
      <xsd:enumeration value="ms"/>
      <xsd:enumeration value="us"/>
      <xsd:enumeration value="ns"/>
    </xsd:restriction>
  </xsd:simpleType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  WaitKind  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:simpleType name="WaitKind">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Transient"/>
      <xsd:enumeration value="Persistent"/>
    </xsd:restriction>
  </xsd:simpleType>

  <!-- ================================================== -->
  <!-- ============  Complex Type Definitions ===========  -->
  <!-- ================================================== -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ActiveResource  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ActiveResource">
    <xsd:complexContent>
      <xsd:extension base="GeneralResource">
        <xsd:sequence>
          <xsd:element name="opTime" type="xsd:string"/>
          <xsd:element default="ms" name="unit" type="TimeUnit"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Actor  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Actor">
    <xsd:complexContent>
      <xsd:extension base="GRLLinkableElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="collapsedRefs" type="xsd:IDREF"/> 
                       <!-- CollapsedActorRef -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="actorRefs" type="xsd:IDREF"/> <!-- ActorRef -->
          <xsd:element minOccurs="0" name="style" type="ConcreteStyle"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="elems" type="xsd:IDREF"/> 
                       <!-- IntentionalElement -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ActorRef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ActorRef">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element name="label" type="Label"/>
          <xsd:element name="actorDef" type="xsd:IDREF"/> <!-- Actor -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="nodes" type="xsd:IDREF"/> <!-- GRLNode -->
          <xsd:element name="pos" type="Position"/>
          <xsd:element name="size" type="Size"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  AndFork  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="AndFork">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  AndJoin  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="AndJoin">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ClosedWorkload  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ClosedWorkload">
    <xsd:complexContent>
      <xsd:extension base="Workload">
        <xsd:sequence>
          <xsd:element name="population" type="xsd:string"/>
          <xsd:element name="externalDelay" type="xsd:string"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  CollapsedActorRef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="CollapsedActorRef">
    <xsd:complexContent>
      <xsd:extension base="GRLNode">
        <xsd:sequence>
                <xsd:element name="actor" type="xsd:IDREF"/> <!-- Actor -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Comment  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Comment">
    <xsd:sequence>
      <xsd:element name="description" type="xsd:string"/>
      <xsd:element name="x" type="xsd:integer"/>
      <xsd:element name="y" type="xsd:integer"/>
      <xsd:element name="width" type="xsd:integer"/>
      <xsd:element name="height" type="xsd:integer"/>
      <xsd:element name="fillColor" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Component  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Component">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element name="kind" type="ComponentKind"/>
          <xsd:element name="protected" type="xsd:boolean"/>
          <xsd:element name="context" type="xsd:boolean"/>
          <xsd:element minOccurs="0" name="type" type="xsd:IDREF"/> <!-- ComponentType -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="includedComponents" type="xsd:IDREF"/>  
                       <!-- Component -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="includingComponents" type="xsd:IDREF"/>  
                       <!-- Component -->
          <xsd:element minOccurs="0" name="host" type="xsd:IDREF"/> <!-- ProcessingResource -->
          <xsd:element minOccurs="0" name="resource" type="xsd:IDREF"/> <!-- PassiveResource -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="compRefs" type="xsd:IDREF"/> 
                       <!-- ComponentRef -->
          <xsd:element minOccurs="0" name="style" type="ConcreteStyle"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ComponentBinding  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ComponentBinding">
    <xsd:sequence>
      <xsd:element name="id" type="xsd:ID" /> <!-- ADDED because ComponentBinding is not a URNmodelElement (no ID) -->
      <xsd:element name="parentComponent" type="xsd:IDREF"/> <!-- ComponentRef -->
      <xsd:element name="pluginComponent" type="xsd:IDREF"/> <!-- ComponentRef -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ComponentRef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ComponentRef">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
                <xsd:element maxOccurs="unbounded" minOccurs="0" name="parentBindings" type="xsd:IDREF"/> 
                       <!-- ComponentBinding -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="pluginBindings" type="xsd:IDREF"/>  
                       <!-- ComponentBinding -->
          <xsd:element name="compDef" type="xsd:IDREF"/>  <!-- Component -->
          <xsd:element minOccurs="0" name="label" type="Label"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="children" type="xsd:IDREF"/>  <!-- ComponentRef -->
          <xsd:element minOccurs="0" name="parent" type="xsd:IDREF"/>  <!-- ComponentRef -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="nodes" type="xsd:IDREF"/>  <!-- PathNode -->
          <xsd:element minOccurs="0" name="pos" type="Position"/>
          <xsd:element minOccurs="0" name="size" type="Size"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ComponentType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ComponentType">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="instances" type="xsd:IDREF"/>  <!-- Component -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Concern  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Concern">
    <xsd:complexContent>
      <xsd:extension base="URNmodelElement">
        <xsd:sequence>
          <xsd:element minOccurs="0" name="condition" type="Condition"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="elements" type="xsd:IDREF"/> 
                       <!-- URNmodelElement -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ConcreteCondition  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ConcreteCondition">
    <xsd:sequence>
      <xsd:element name="label" type="xsd:string"/>
      <xsd:element name="description" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ConcreteGRLspec  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ConcreteGRLspec">
    <xsd:sequence>
      <xsd:element name="showAsMeansEnd" type="xsd:boolean"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ConcreteStyle  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ConcreteStyle">
    <xsd:sequence>
      <xsd:element name="lineColor" type="xsd:string"/>
      <xsd:element name="fillColor" type="xsd:string"/>
      <xsd:element name="filled" type="xsd:boolean"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ConcreteURNspec  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ConcreteURNspec">
    <xsd:sequence>
      <xsd:element name="description" type="xsd:string"/>
      <xsd:element name="author" type="xsd:string"/>
      <xsd:element name="created" type="xsd:string"/>
      <xsd:element name="modified" type="xsd:string"/>
      <xsd:element name="specVersion" type="xsd:string"/>
      <xsd:element name="urnVersion" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Condition  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Condition">
    <xsd:sequence>
      <xsd:element name="expression" type="xsd:string"/>
      <xsd:element minOccurs="0" name="desc" type="ConcreteCondition"/>
      <xsd:element minOccurs="0" name="label" type="Label"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Connect  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Connect">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Contribution  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Contribution">
    <xsd:complexContent>
      <xsd:extension base="ElementLink">
        <xsd:sequence>
          <xsd:element default="Unknown" name="contribution" type="ContributionType"/>
          <xsd:element name="quantitativeContribution" type="xsd:integer"/>
          <xsd:element name="correlation" type="xsd:boolean"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Decomposition  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Decomposition">
    <xsd:complexContent>
      <xsd:extension base="ElementLink"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Demand  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Demand">
    <xsd:sequence>
      <xsd:element name="quantity" type="xsd:string"/>
      <xsd:element name="resource" type="xsd:IDREF"/> <!-- ExternalOperation -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Dependency  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Dependency">
    <xsd:complexContent>
      <xsd:extension base="ElementLink"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Description  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Description">
    <xsd:sequence>
      <xsd:element name="description" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  DirectionArrow  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="DirectionArrow">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ElementLink  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ElementLink">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="refs" type="xsd:IDREF"/> <!-- LinkRef -->
          <xsd:element name="dest" type="xsd:IDREF"/> <!-- GRLLinkableElement -->
          <xsd:element name="src" type="xsd:IDREF"/> <!-- GRLLinkableElement -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  EmptyPoint  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="EmptyPoint">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  EndPoint  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="EndPoint">
    <xsd:complexContent>
      <xsd:extension base="PathNode">
        <xsd:sequence>
                <xsd:element maxOccurs="unbounded" minOccurs="0" name="outBindings" type="xsd:IDREF"/> 
                       <!-- OutBinding -->
          <xsd:element minOccurs="0" name="postcondition" type="Condition"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  EnumerationType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="EnumerationType">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element name="values" type="xsd:string"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="instances" type="xsd:IDREF"/> <!-- Variable -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Evaluation  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Evaluation">
    <xsd:sequence>
      <xsd:element name="evaluation" type="xsd:integer"/>
      <xsd:element default="None" name="qualitativeEvaluation" type="QualitativeLabel"/>
      <xsd:element name="intElement" type="xsd:IDREF"/>  <!-- IntentionalElement -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  EvaluationStrategy  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="EvaluationStrategy">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="evaluations" type="Evaluation"/>
          <xsd:element maxOccurs="unbounded" name="group" type="xsd:IDREF"/> <!-- StrategiesGroup -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ExternalOperation  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ExternalOperation">
    <xsd:complexContent>
      <xsd:extension base="ActiveResource">
        <xsd:sequence>
                <xsd:element maxOccurs="unbounded" minOccurs="0" name="demands" type="xsd:IDREF"/> <!-- Demand -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  GeneralResource  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="GeneralResource">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element default="1" name="multiplicity" type="xsd:nonNegativeInteger"/>
          <xsd:element name="schedPolicy" type="xsd:string"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  GRLGraph  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="GRLGraph">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="connections" type="LinkRef"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="nodes" type="GRLNode"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="contRefs" type="ActorRef"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="comments" type="Comment"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  GRLLinkableElement  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="GRLLinkableElement">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="linksDest" type="xsd:IDREF"/> <!-- ElementLink -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="linksSrc" type="xsd:IDREF"/> <!-- ElementLink -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  GRLmodelElement  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="GRLmodelElement">
    <xsd:complexContent>
      <xsd:extension base="URNmodelElement"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  GRLNode  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="GRLNode">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="pred" type="xsd:IDREF"/> <!-- LinkRef -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="succ" type="xsd:IDREF"/> <!-- LinkRef -->
          <xsd:element minOccurs="0" name="contRef" type="xsd:IDREF"/> <!-- ActorRef -->
          <xsd:element name="pos" type="Position"/>
          <xsd:element name="size" type="Size"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  GRLspec  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="GRLspec">
    <xsd:sequence>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="intElements" type="IntentionalElement"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="actors" type="Actor"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="links" type="ElementLink"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="groups" type="StrategiesGroup"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="strategies" type="EvaluationStrategy"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="grlGraphs" type="GRLGraph"/>
      <xsd:element minOccurs="0" name="info" type="ConcreteGRLspec"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  InBinding  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="InBinding">
    <xsd:sequence>
      <xsd:element name="id" type="xsd:ID" /> <!-- ADDED because InBinding is not a URNmodelElement (no ID) -->
      <xsd:element name="startPoint" type="xsd:IDREF"/>  <!-- StartPoint -->
      <xsd:element name="stubEntry" type="xsd:IDREF"/>  <!-- NodeConnection -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Initialization  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Initialization">
    <xsd:sequence>
      <xsd:element name="value" type="xsd:string"/>
      <xsd:element name="variable" type="xsd:IDREF"/>  <!-- Variable -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  IntentionalElement  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="IntentionalElement">
    <xsd:complexContent>
      <xsd:extension base="GRLLinkableElement">
        <xsd:sequence>
          <xsd:element name="type" type="IntentionalElementType"/>
          <xsd:element default="AND" name="decompositionType" type="DecompositionType"/>
          <xsd:element default="None" name="importance" type="ImportanceType"/>
          <xsd:element name="importanceQuantitative" type="xsd:integer"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="refs" type="xsd:IDREF"/>  
                       <!-- IntentionalElementRef -->
          <xsd:element minOccurs="0" name="style" type="ConcreteStyle"/>
          <xsd:element minOccurs="0" name="actor" type="xsd:IDREF"/> <!-- Actor -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  IntentionalElementRef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="IntentionalElementRef">
    <xsd:complexContent>
      <xsd:extension base="GRLNode">
        <xsd:sequence>
          <xsd:element name="def" type="xsd:IDREF"/> <!-- IntentionalElement -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Label  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Label">
    <xsd:sequence>
      <xsd:element name="deltaX" type="xsd:integer"/>
      <xsd:element name="deltaY" type="xsd:integer"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  LinkRef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="LinkRef">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element name="curve" type="xsd:boolean"/>
          <xsd:element name="link" type="xsd:IDREF"/>  <!-- ElementLink -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="bendpoints" type="LinkRefBendpoint"/> 
                       <!-- {ordered} -->
          <xsd:element minOccurs="0" name="label" type="Label"/>
          <xsd:element name="target" type="xsd:IDREF"/>  <!-- GRLNode -->
          <xsd:element name="source" type="xsd:IDREF"/>  <!-- GRLNode -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  LinkRefBendpoint  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="LinkRefBendpoint">
    <xsd:sequence>
      <xsd:element name="x" type="xsd:integer"/>
      <xsd:element name="y" type="xsd:integer"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Metadata  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Metadata">
    <xsd:sequence>
      <xsd:element name="name" type="xsd:string"/>
      <xsd:element name="value" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  NodeConnection  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="NodeConnection">
    <xsd:sequence>
      <xsd:element name="id" type="xsd:ID"/> <!-- ADDED because NodeConnection is not a URNmodelElement 
                        (no ID) -->         
      <xsd:element default="100" name="probability" type="xsd:nonNegativeInteger"/>
      <xsd:element name="threshold" type="xsd:string"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="inBindings" type="xsd:IDREF"/> <!-- InBinding -->
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="outBindings" type="xsd:IDREF"/> <!-- OutBinding -->
      <xsd:element minOccurs="0" name="condition" type="Condition"/>
      <xsd:element minOccurs="0" name="timer" type="xsd:IDREF"/> <!-- Timer -->
      <xsd:element minOccurs="0" name="label" type="Label"/>
      <xsd:element name="target" type="xsd:IDREF"/> <!-- PathNode -->
      <xsd:element name="source" type="xsd:IDREF"/> <!-- PathNode -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OWPeriodic  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OWPeriodic">
    <xsd:complexContent>
      <xsd:extension base="OpenWorkload">
        <xsd:sequence>
          <xsd:element name="period" type="xsd:string"/>
          <xsd:element name="deviation" type="xsd:string"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OWPhaseType  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OWPhaseType">
    <xsd:complexContent>
      <xsd:extension base="OpenWorkload">
        <xsd:sequence>
          <xsd:element name="alpha" type="xsd:string"/>
          <xsd:element name="s" type="xsd:string"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OWPoisson  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OWPoisson">
    <xsd:complexContent>
      <xsd:extension base="OpenWorkload">
        <xsd:sequence>
          <xsd:element name="mean" type="xsd:string"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OWUniform  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OWUniform">
    <xsd:complexContent>
      <xsd:extension base="OpenWorkload">
        <xsd:sequence>
          <xsd:element name="start" type="xsd:string"/>
          <xsd:element name="end" type="xsd:string"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OpenWorkload  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OpenWorkload">
    <xsd:complexContent>
      <xsd:extension base="Workload"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OrFork  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OrFork">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OrJoin  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OrJoin">
    <xsd:complexContent>
      <xsd:extension base="PathNode"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  OutBinding  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="OutBinding">
    <xsd:sequence>
      <xsd:element name="id" type="xsd:ID" /> <!-- ADDED because OutBinding is not a URNmodelElement (no ID) -->
      <xsd:element name="endPoint" type="xsd:IDREF"/> <!-- EndPoint -->
      <xsd:element name="stubExit" type="xsd:IDREF"/> <!-- NodeConnection -->
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  PassiveResource  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="PassiveResource">
    <xsd:complexContent>
      <xsd:extension base="GeneralResource">
        <xsd:sequence>
          <xsd:element minOccurs="0" name="component" type="xsd:IDREF"/> <!-- Component -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  PathNode  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="PathNode">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element minOccurs="0" name="label" type="Label"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="pred" type="xsd:IDREF"/> 
                       <!-- NodeConnection -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="succ" type="xsd:IDREF"/> 
                       <!-- NodeConnection -->
          <xsd:element minOccurs="0" name="contRef" type="xsd:IDREF"/> <!-- ComponentRef -->
          <xsd:element minOccurs="0" name="pos" type="Position"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  PluginBinding  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="PluginBinding">
    <xsd:sequence>
      <xsd:element name="id" type="xsd:ID"/> <!-- ADDED because PluginBinding is not a URNmodelElement (no ID) -->
      <xsd:element default="100" name="probability" type="xsd:nonNegativeInteger"/>
      <xsd:element name="replicationFactor" type="xsd:string"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="in" type="InBinding"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="out" type="OutBinding"/>
      <xsd:element name="plugin" type="xsd:IDREF"/> <!-- UCMmap -->
      <xsd:element minOccurs="0" name="precondition" type="Condition"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="components" type="ComponentBinding"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Position  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Position">
    <xsd:sequence>
      <xsd:element name="x" type="xsd:integer"/>
      <xsd:element name="y" type="xsd:integer"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ProcessingResource  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ProcessingResource">
    <xsd:complexContent>
      <xsd:extension base="ActiveResource">
        <xsd:sequence>
          <xsd:element default="Processor" name="kind" type="DeviceKind"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="components" type="xsd:IDREF"/> 
                       <!-- Component -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Responsibility  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Responsibility">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element name="expression" type="xsd:string"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="demands" type="Demand"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="respRefs" type="xsd:IDREF"/> <!-- RespRef -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  RespRef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="RespRef">
    <xsd:complexContent>
      <xsd:extension base="PathNode">
        <xsd:sequence>
          <xsd:element name="repetitionCount" type="xsd:string"/>
          <xsd:element name="hostDemand" type="xsd:string"/>
          <xsd:element name="respDef" type="xsd:IDREF"/> <!-- Responsibility -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ScenarioDef  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ScenarioDef">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="initializations" type="Initialization"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="postconditions" type="Condition"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="preconditions" type="Condition"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="parentScenarios" type="xsd:IDREF"/>  
                       <!-- ScenarioDef -->
          <xsd:element minOccurs="0" name="includedScenarios" type="xsd:IDREFS"/>  
                       <!-- ScenarioDef {ordered} -->
          <xsd:element maxOccurs="unbounded" name="groups" type="xsd:IDREF"/> <!-- ScenarioGroup -->
          <xsd:element minOccurs="0" name="startPoints" type="xsd:IDREFS"/>  <!-- StartPoint {ordered} -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="endPoints" type="xsd:IDREF"/>  
                       <!-- EndPoint -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  ScenarioGroup  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="ScenarioGroup">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="scenarios" type="xsd:IDREF"/> 
                       <!-- ScenarioDef -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Size  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Size">
    <xsd:sequence>
      <xsd:element name="width" type="xsd:integer"/>
      <xsd:element name="height" type="xsd:integer"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  StartPoint  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="StartPoint">
    <xsd:complexContent>
      <xsd:extension base="PathNode">
        <xsd:sequence>
          <xsd:element minOccurs="0" name="workload" type="Workload"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="inBindings" type="xsd:IDREF"/> 
                       <!-- InBinding -->
          <xsd:element minOccurs="0" name="precondition" type="Condition"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  StrategiesGroup  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="StrategiesGroup">
    <xsd:complexContent>
      <xsd:extension base="GRLmodelElement">
        <xsd:sequence>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="strategies" type="xsd:IDREF"/> 
                       <!-- EvaluationStrategy -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Stub  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Stub">
    <xsd:complexContent>
      <xsd:extension base="PathNode">
        <xsd:sequence>
          <xsd:element name="dynamic" type="xsd:boolean"/>
          <xsd:element name="synchronizing" type="xsd:boolean"/>
          <xsd:element name="blocking" type="xsd:boolean"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="bindings" type="PluginBinding"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Timer  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Timer">
    <xsd:complexContent>
      <xsd:extension base="WaitingPlace">
        <xsd:sequence>
          <xsd:element minOccurs="0" name="timeoutPath" type="xsd:IDREF"/> <!-- NodeConnection -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  UCMmap  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="UCMmap">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element name="singleton" type="xsd:boolean"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="parentStub" type="xsd:IDREF"/> 
                       <!-- PluginBinding -->
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="contRefs" type="ComponentRef"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="connections" type="NodeConnection"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="nodes" type="PathNode"/>
          <xsd:element maxOccurs="unbounded" minOccurs="0" name="comments" type="Comment"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  UCMmodelElement  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="UCMmodelElement">
    <xsd:complexContent>
      <xsd:extension base="URNmodelElement"/>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  UCMspec  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="UCMspec">
    <xsd:sequence>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="enumerationTypes" type="EnumerationType"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="variables" type="Variable"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="scenarioGroups" type="ScenarioGroup"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="resources" type="GeneralResource"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="ucmMaps" type="UCMmap"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="components" type="Component"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="componentTypes" type="ComponentType"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="responsibilities" type="Responsibility"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="scenarioDefs" type="ScenarioDef"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  URNlink  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="URNlink">
    <xsd:complexContent>
      <xsd:extension base="URNmodelElement">
        <xsd:sequence>
          <xsd:element name="type" type="xsd:string"/>
          <xsd:element name="toElem" type="xsd:IDREF"/> <!-- URNmodelElement -->
          <xsd:element name="fromElem" type="xsd:IDREF"/> <!-- URNmodelElement -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  URNmodelElement  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="URNmodelElement">
    <xsd:sequence>
      <xsd:element name="id" type="xsd:ID"/>
      <xsd:element name="name" type="xsd:string"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="metadata" type="Metadata"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="toLinks" type="xsd:IDREF"/> <!-- URNlink -->
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="fromLinks" type="xsd:IDREF"/> <!-- URNlink -->
      <xsd:element minOccurs="0" name="desc" type="Description"/>
      <xsd:element minOccurs="0" name="concern" type="xsd:IDREF"/> <!-- Concern -->
    </xsd:sequence>	
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  URNspec  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="URNspec">
    <xsd:sequence>
      <xsd:element name="name" type="xsd:string"/>
      <xsd:element minOccurs="0" name="ucmspec" type="UCMspec"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="metadata" type="Metadata"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="urnLinks" type="URNlink"/>
      <xsd:element minOccurs="0" name="grlspec" type="GRLspec"/>
      <xsd:element minOccurs="0" name="info" type="ConcreteURNspec"/>
      <xsd:element maxOccurs="unbounded" minOccurs="0" name="concerns" type="Concern"/>
    </xsd:sequence>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Variable  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Variable">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element default="Boolean" name="type" type="DatatypeKind"/>
          <xsd:element minOccurs="0" name="enumerationType" type="xsd:IDREF"/> <!-- EnumerationType -->
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  WaitingPlace  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="WaitingPlace">
    <xsd:complexContent>
      <xsd:extension base="PathNode">
        <xsd:sequence>
          <xsd:element name="waitType" type="WaitKind"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!--  Workload  -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <xsd:complexType name="Workload">
    <xsd:complexContent>
      <xsd:extension base="UCMmodelElement">
        <xsd:sequence>
          <xsd:element default="ms" name="unit" type="TimeUnit"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
</xsd:schema>