
http://noble.gs.washington.edu/proj/genomedata/doc/1.2.2/genomedata.html#genomedata-version-documentation

For a broad overview, see the paper:

Hoffman MM, Buske OJ, Noble WS. (2010). The Genomedata format for storing large-scale functional genomics data. Bioinformatics, 26(11):1458-1459; doi:10.1093/bioinformatics/btq164
Please cite this paper if you use Genomedata.