GraphML is an XML-based file format for storing a single undirected or directed graph.

The GraphTheory[ImportGraph] and GraphTheory[ExportGraph] commands can read from and write to this format.

The general-purpose commands Import and Export also support this format.

$\mathrm{Petersen}≔\mathrm{Import}\left(''example/petersen.graphml''\,\mathrm{base}=\mathrm{datadir}\right)$

$\mathrm{Petersen}≔\mathrm{Graph\; 1:\; an\; undirected\; graph\; with\; 10\; vertices\; and\; 15\; edge(s)}$

$\mathrm{GraphTheory}:-\mathrm{DrawGraph}\left(\mathrm{Petersen}\,\mathrm{style}=\mathrm{spring}\right)$

$\mathrm{CG}≔\mathrm{GraphTheory}:-\mathrm{SpecialGraphs}:-\mathrm{ClebschGraph}\left(\right)$

$\mathrm{CG}≔\mathrm{Graph\; 2:\; an\; undirected\; graph\; with\; 16\; vertices\; and\; 40\; edge(s)}$

$\mathrm{Export}\left(''clebsch.graphml''\,\mathrm{CG}\,\mathrm{base}=\mathrm{homedir}\right)$

$4351$

GraphML Specification, graphdrawing.org.