<!-- GXL (1.0.1) 
     Document Type Definition
     (April 25, 2002) 
  
copyright by 

       Andy Schuerr 
         Institute for Software Technology 
         University of the German Federal Armed Forces Munich 
         85577 Neubiberg, Germany 
         Andy.Schuerr@unibw-muenchen.de 

       Susan Elliott Sim 
         Department of Computer Science 
         University of Toronto 
         Toronto M5S 3G4, Canada 
         simsuz@cs.utoronto.ca 

       Ric Holt 
         Department of Computer Science 
         University of Waterloo 
         Waterloo N2L 3G1, Canada 
         holt@plg.uwaterloo.ca 

       Andreas Winter 
         Institute for Software Technology 
         University of Koblenz-Landau 
         Rheinau 1, D-56075 Koblenz, Germany 
         winter@uni-koblenz.de
-->
<!-- Extensions -->
<!ENTITY % gxl-extension "">
<!ENTITY % graph-extension "">
<!ENTITY % node-extension "">
<!ENTITY % edge-extension "">
<!ENTITY % rel-extension "">
<!ENTITY % value-extension "">
<!ENTITY % relend-extension "">
<!ENTITY % gxl-attr-extension "">
<!ENTITY % graph-attr-extension "">
<!ENTITY % node-attr-extension "">
<!ENTITY % edge-attr-extension "">
<!ENTITY % rel-attr-extension "">
<!ENTITY % relend-attr-extension "">
<!-- Attribute values -->
<!ENTITY % val " 
           locator | 
           bool    | 
           int     | 
           float   | 
           string  | 
           enum    | 
           seq     | 
           set     | 
           bag     | 
           tup 
           %value-extension;">
<!-- gxl -->
<!ELEMENT gxl (graph* %gxl-extension;) >
<!ATTLIST gxl
	xmlns:xlink CDATA #FIXED "http://www.w3.org/1999/xlink"
	%gxl-attr-extension; 
>
<!-- type -->
<!ELEMENT type EMPTY>
<!ATTLIST type
	xlink:type (simple) #FIXED "simple"
	xlink:href CDATA #REQUIRED
>
<!-- graph -->
<!ELEMENT graph (type? , attr* , ( node | edge | rel )* %graph-extension;) >
<!ATTLIST graph
	id ID #REQUIRED
	role NMTOKEN #IMPLIED
	edgeids (true | false) "false"
	hypergraph (true | false) "false"
	edgemode (directed | undirected | defaultdirected | defaultundirected) "directed"
	%graph-attr-extension; 
>
<!-- node -->
<!ELEMENT node (type? , attr*, graph* %node-extension;) >
<!ATTLIST node
	id ID #REQUIRED
	%node-attr-extension; 
>
<!-- edge -->
<!ELEMENT edge (type?, attr*, graph* %edge-extension;) >
<!ATTLIST edge
	id ID #IMPLIED
	from IDREF #REQUIRED
	to IDREF #REQUIRED
	fromorder CDATA #IMPLIED
	toorder CDATA #IMPLIED
	isdirected (true | false) #IMPLIED
	%edge-attr-extension; 
>
<!-- rel -->
<!ELEMENT rel (type? , attr*, graph*, relend* %rel-extension;) >
<!ATTLIST rel
	id ID #IMPLIED
	isdirected (true | false) #IMPLIED
	%rel-attr-extension; 
>
<!-- relend -->
<!ELEMENT relend (attr* %relend-extension;) >
<!ATTLIST relend
	target IDREF #REQUIRED
	role NMTOKEN #IMPLIED
	direction (in | out | none) #IMPLIED
	startorder CDATA #IMPLIED
	endorder CDATA #IMPLIED
	%relend-attr-extension; 
>
<!-- attr -->
<!ELEMENT attr (type?, attr*, (%val;))>
<!ATTLIST attr
	id ID #IMPLIED
	name NMTOKEN #REQUIRED
	kind NMTOKEN #IMPLIED
>
<!-- locator -->
<!ELEMENT locator EMPTY>
<!ATTLIST locator
	xlink:type (simple) #FIXED "simple"
	xlink:href CDATA #REQUIRED
>
<!-- atomic values -->
<!ELEMENT bool (#PCDATA)>
<!ELEMENT int (#PCDATA)>
<!ELEMENT float (#PCDATA)>
<!ELEMENT string (#PCDATA)>
<!-- enumeration value -->
<!ELEMENT enum (#PCDATA)>
<!-- composite values -->
<!ELEMENT seq (%val;)*>
<!ELEMENT set (%val;)*>
<!ELEMENT bag (%val;)*>
<!ELEMENT tup (%val;)*>