ESW Wiki - DmozRdf
"While the dumps are frequently referred to as being RDF, they are actually not, exactly. The ODP data dump format was created by one of the architechs of the w3c RDF standard but this happened before the standard was completed. As it turned out, the standard diverged quite a bit from the format used in the ODP dump by the time it was finalized." Describes what the data file actually is, and how to parse it.