<!ELEMENT gexf (meta? , graph)>
	<!ATTLIST gexf version CDATA #REQUIRED>
	<!ATTLIST gexf variant CDATA #IMPLIED>
	<!ELEMENT meta (creator , keywords, description, lastModifiedDate)>
		<!ELEMENT creator (#PCDATA)>
		<!ELEMENT keywords (#PCDATA)>
		<!ELEMENT description (#PCDATA)>
		<!ELEMENT lastModifiedDate (#PCDATA)>
	<!ELEMENT graph (attributes*, nodes, edges)>
		<!ATTLIST graph type (static|dynamic) #REQUIRED>
		<!ATTLIST graph levels CDATA #IMPLIED>
		<!ATTLIST graph edges (simple|directed|double) #IMPLIED>
		<!ATTLIST graph datefrom CDATA #IMPLIED>
		<!ATTLIST graph dateto CDATA #IMPLIED>
		<!ELEMENT attributes (attribute*)>
			<!ATTLIST attributes type (static|dynamic) #REQUIRED>
			<!ATTLIST attributes class (node|edge) #REQUIRED>
			<!ATTLIST attributes classlevel CDATA #IMPLIED>
			<!ATTLIST attributes datefrom CDATA #IMPLIED>
			<!ATTLIST attributes dateto CDATA #IMPLIED>
			<!ELEMENT attribute EMPTY>
				<!ATTLIST attribute id CDATA #REQUIRED>
				<!ATTLIST attribute title CDATA #REQUIRED>
				<!ATTLIST attribute type (integer|double|float|boolean|liststring|string) #REQUIRED>
				<!ATTLIST attribute default CDATA #IMPLIED>
		<!ELEMENT nodes (node*, edges?)>
			<!ATTLIST nodes count CDATA #IMPLIED>
			<!ATTLIST nodes level CDATA #IMPLIED>
			<!ELEMENT node (attvalues?, nodes?)>
				<!ATTLIST node id CDATA #REQUIRED>
				<!ATTLIST node pid CDATA #IMPLIED>
				<!ATTLIST node label CDATA #REQUIRED>
				<!ATTLIST node datefrom CDATA #IMPLIED>
				<!ATTLIST node dateto CDATA #IMPLIED>
				<!ELEMENT attvalues (attvalue*)>
					<!ELEMENT attvalue EMPTY>
						<!ATTLIST attvalue id CDATA #REQUIRED>
						<!ATTLIST attvalue value CDATA #REQUIRED>
						<!ATTLIST attvalue datefrom CDATA #IMPLIED>
						<!ATTLIST attvalue dateto CDATA #IMPLIED>
		<!ELEMENT edges (edge*)>
			<!ELEMENT edge (attvalues?)>
				<!ATTLIST edge id CDATA #REQUIRED>
				<!ATTLIST edge source CDATA #REQUIRED>
				<!ATTLIST edge target CDATA #REQUIRED>
				<!ATTLIST edge cardinal CDATA #IMPLIED>
				<!ATTLIST edge type (sim|dir|dou) #IMPLIED>