B. GraphML
GraphML (Graph Markup Language) [2] is a
comprehensive and easy-to-use file format for graphs. It
consists of a language core (known as the Structural Layer)
to describe structural properties of one or more graphs and a
flexible extension mechanism, e.g. to add application-
specific data. Its main features include support of directed,
undirected, mixed multigraphs, hypergraphs, hierarchical
graphs, attributed graphs, multiple graphs in a single file,
application-specific data, and references to external data.
Two extensions, adding support of meta-information for
light-weight parsers (Parse Extension) and typed attribute
data (Attributes Extension) are currently part of the
GraphML specification.
Unlike many other file formats for graphs, GraphML
does not use a custom syntax. Instead, it is defined as an
XML (Extensible Markup Language) sublanguage and hence
ideally suited as an exchange format for all kinds of services
generating or processing graphs