The CGXML Format
Disclaimer: this format is only a draft and probably never be an official format for CGs.
The CGXML format is defined using an XML Schema, the current version can be found at http://tockit.sf.net/cgxml/schema/cgxml20010821.xsd. A short overview of the format follows, there is also a more complete documentation.
CGXML offers two starting element, one for single graphs and one for a complete knowledge base (module). We tried to model the structure as explicit as possible to allow easy access and control for the parts which results in a quite verbose but easy to handle format. The XML Schema file contains a number of annotations, a more complete rationale should follow once the format is more stable.
Here is a diagram of the graph definition (click to enlarge):
And here a very early version for the modules: