<!ELEMENT SystemDefinition (systemModel?, build?)>

  <!ATTLIST SystemDefinition

   name CDATA #REQUIRED

   schema CDATA #REQUIRED>

  <!ELEMENT systemModel (layer+)>

  <!ELEMENT layer (logicalset* | module*)*>

  <!ATTLIST layer

   name CDATA #REQUIRED

   levels CDATA #IMPLIED

   span CDATA #IMPLIED>

  <!ELEMENT logicalset (logicalsubset* | module* | unit* | package* | prebuilt*)*>

  <!ATTLIST logicalset name CDATA #REQUIRED>

  <!ELEMENT logicalsubset (module* | unit* | package* | prebuilt*)*>

  <!ATTLIST logicalsubset name CDATA #REQUIRED>

  <!ELEMENT module (component* | unit* | package* | prebuilt*)*>

  <!ATTLIST module

   name CDATA #REQUIRED

   level CDATA #IMPLIED>

  <!ELEMENT component (unit* | package* | prebuilt*)*>

  <!ATTLIST component name CDATA #REQUIRED>

  <!ELEMENT unit EMPTY>

  <!ATTLIST unit

   unitID ID #REQUIRED

   name CDATA #REQUIRED

   mrp CDATA #REQUIRED

   filter CDATA #IMPLIED

   bldFile CDATA #REQUIRED

   priority CDATA #IMPLIED

   contract CDATA #IMPLIED>

  <!ELEMENT package EMPTY>

  <!ATTLIST package

   name CDATA #REQUIRED

   mrp CDATA #REQUIRED

   filter CDATA #IMPLIED

   contract CDATA #IMPLIED>

  <!ELEMENT prebuilt EMPTY>

  <!ATTLIST prebuilt

   name CDATA #REQUIRED

   version CDATA #REQUIRED

   late (Y|N) #IMPLIED

   filter CDATA #IMPLIED

   contract CDATA #IMPLIED>

  <!ELEMENT build (option* | target+ | targetList+ | unitList+ | configuration+)*>

  <!ELEMENT unitList (unitRef+)>

  <!ATTLIST unitList

   name ID #REQUIRED

   description CDATA #REQUIRED>

  <!ELEMENT unitRef EMPTY>

  <!ATTLIST unitRef unit IDREF #REQUIRED>

  <!ELEMENT targetList EMPTY>

  <!ATTLIST targetList

   name ID #REQUIRED

   description CDATA #REQUIRED

   target IDREFS #REQUIRED>

  <!ELEMENT target EMPTY>

  <!ATTLIST target

   name ID #REQUIRED

   abldTarget CDATA #REQUIRED

   description CDATA #REQUIRED>

  <!ELEMENT option EMPTY>

  <!ATTLIST option

   name ID #REQUIRED

   abldOption CDATA #REQUIRED

   description CDATA #REQUIRED

   enable (Y | N | y | n) #REQUIRED>

  <!ELEMENT configuration (unitListRef+ | layerRef+ | task+)*>

  <!ATTLIST configuration

   name ID #REQUIRED

   description CDATA #REQUIRED

   filter CDATA #REQUIRED>

  <!ELEMENT task ( unitListRef* , (buildLayer | specialInstructions))>

  <!ELEMENT unitListRef EMPTY>

  <!ATTLIST unitListRef unitList IDREF #REQUIRED>

  <!ELEMENT layerRef EMPTY>

  <!ATTLIST layerRef layerName CDATA #REQUIRED>

  <!ELEMENT buildLayer EMPTY>

  <!ATTLIST buildLayer

   command CDATA #REQUIRED

   targetList IDREFS #IMPLIED

   unitParallel (Y | N | y | n) #REQUIRED

   targetParallel (Y | N | y | n) #IMPLIED>

  <!ELEMENT specialInstructions EMPTY>

  <!ATTLIST specialInstructions

   name CDATA #REQUIRED

   cwd CDATA #REQUIRED

   command CDATA #REQUIRED>