Data—Collect, Clean, and Connect - Graph Analysis and Visualization - page 95

GraphML provides useful features such as data type identifiers, as is shown
in the top section of the following sample file:
<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns">
<key id="NodeLabel" attr.name="Label"
attr.type="string" for="node" />
<key id="NumMail" attr.name="NumMail"
attr.type="double" for="node" />
<key id="TotalKb" attr.name="TotalKb"
attr.type="double" for="node" />
<key id="NumMsg" attr.name="NumMsg"
attr.type="double" for="edge" />
<graph edgedefault="undirected">
<node id="Ann">
<data key="NodeLabel">Ann</data>
<data key="NumEmail">1</data>
<data key="TotalKb">2048</data>
</node>
<node id="Ben">
<data key="NodeLabel">Ben</data>
<data key="NumEmail">4</data>
<data key="TotalKb">7687</data>
</node>
... more nodes ...
<edge source="Ann" target="Ben">
<data key="NumMsg">1</data>
</edge>
... more edges ...
</graph>
</graphml>
Note
GraphML is well documented at http://graphml.graphdrawing.org/
primer/graphml-primer.html .
JavaScript Object Notation (JSON) is a different open standard
alternative to XML that works well with JavaScript and web-based