Some other bits of information which might help the programmers:

https://github.com/LA3QMA/TM-V71_TM-D710-Kenwood

http://n3ujj.com/manuals/control_commands.pdf

http://www.radiomanual.info/schemi/KENW_VU/TH-F6A_TH-F7E_protocol_informations.pdf
(might give some ideas)