GraphML用于定义图形（graph）,对于下面的一个简单图形，
用GraphML描述为：
<?xmlversion="1.0"encoding="UTF-8"?><graphmlxmlns="http://graphml.graphdrawing.org/xmlns"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://graphml.graphdrawing.org/xmlnshttp://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd"><graphid="G"edgedefault="undirected"><nodeid="n0"/><nodeid="n1"/><nodeid="n2"/><nodeid="n3"/><nodeid="n4"/><nodeid="n5"/><nodeid="n6"/><nodeid="n7"/><nodeid="n8"/><nodeid="n9"/><nodeid="n10"/><edgesource="n0"target="n2"/><edgesource="n1"target="n2"/><edgesource="n2"target="n3"/><edgesource="n3"target="n5"/><edgesource="n3"target="n4"/><edgesource="n4"target="n6"/><edgesource="n6"target="n5"/><edgesource="n5"target="n7"/><edgesource="n6"target="n8"/><edgesource="n8"target="n7"/><edgesource="n8"target="n9"/><edgesource="n8"target="n10"/></graph></graphml>可以看出，GraphML中关于图形的一些基本概念如下：
需要注意以下几点：
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1.Graph中的元素(element)没有顺序要求
如，下面的Graph是正确的：
<graphid="G"edgedefault="directed"><nodeid="n0"/><edgesource="n0"target="n2"/><nodeid="n1"/><nodeid="n2"/></graph>
Graph中必须指定
edgedefault属性(“directed”或“undirected”)，
Edge中也可以单独设置directed 为true或false。