<!-- GXL (1.1)
     Document Type Definition
     (October 9, 2003)

copyright by

       Andy Schuerr
         Real-Time Systems Lab
         Darmstadt University of Technology
         Merckstr. 25, D-64283 Darmstadt, Germany
         andy.schuerr@es.tu-darmstadt.de

       Susan Elliott Sim
         School of Information and Computer Science
         444 Computer Science Bldg.
         University of California, Irvine
         ses@ics.uci.edu

       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
         Universitaetsstrasse 1, D-56070 Koblenz, Germany
         winter@uni-koblenz.de
-->
<!-- Extensions -->
<!ENTITY % graph-extension "">
<!ENTITY % node-extension "">
<!ENTITY % edge-extension "">
<!ENTITY % rel-extension "">
<!ENTITY % relend-extension "">
<!ENTITY % graph-attr-extension "">
<!ENTITY % node-attr-extension "">
<!ENTITY % edge-attr-extension "">
<!ENTITY % rel-attr-extension "">
<!ENTITY % relend-attr-extension "">
<!-- graph -->
<!ELEMENT graph (attr* , ( node | edge | rel )* %graph-extension;) >
<!ATTLIST graph
	id ID #REQUIRED
	type CDATA #IMPLIED
	schema CDATA #IMPLIED
	role NMTOKEN #IMPLIED
	defaultdirected (true | false) "true"
	defaultattrvalidity (valid | unknown) "valid"
	%graph-attr-extension; 
>
<!-- graphref -->
<!ELEMENT graphref EMPTY>
<!ATTLIST graphref
	xlink:type (simple) #FIXED "simple"
	xlink:href CDATA #REQUIRED
>
<!-- node -->
<!ELEMENT node (attr*, (graph|graphref)* %node-extension;) >
<!ATTLIST node
	id ID #REQUIRED
	type CDATA #IMPLIED
	order CDATA #IMPLIED
	%node-attr-extension; 
>
<!-- edge -->
<!ELEMENT edge (attr*, (graph|graphref)* %edge-extension;) >
<!ATTLIST edge
	id ID #IMPLIED
	type CDATA #IMPLIED
	order CDATA #IMPLIED
	from IDREF #REQUIRED
	to IDREF #REQUIRED
	fromorder CDATA #IMPLIED
	toorder CDATA #IMPLIED
	isdirected (true | false) #IMPLIED
	%edge-attr-extension; 
>
<!-- rel -->
<!ELEMENT rel (attr*, (graph|graphref)*, relend* %rel-extension;) >
<!ATTLIST rel
	id ID #IMPLIED
	type CDATA #IMPLIED
	order CDATA #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; 
>