Phil,
I am currently preparing a formal specification of the grammar (based on your draft) which can be fed into flex/bison to generate a GTP command parser. I will integrate this in a very simple application so that one can get a feeling for the behaviour of the protocol by manually feeding it commands and observe the answers. Actually this is already half way done (error recovery is missing yet); I will make it available ASAP. The formal spec perhaps can help to cleanup syntax issues in the GTP docs as well.
Hellwig