<!-- GXL (1.0)
     Document Type Definition
     (April 25, 2002)

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 % 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 (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;)*>