Hello John,

For the RF DV data payload, it's a plain, non-framed format to which anyone can do with what they want.  One example that you might want to check out is the D-RATS program:

   http://d-rats.com/

Very capable program from the same maker as Chirp, written in Python.  Unfortunately, I'm not aware of any other programs that uses the data side of Dstar today.

--David
KI6ZHD