I think this fills my wish for Parse::RecDescent to handle binary data grammars. I did some work parsing Xerox Metacode files (an undocumented binary format for use with volumn printing systems - think printers hooked up to mainframes) and while it was a pain - I would really have preferred to write the description down as a proper grammar and then let the regex engine handle the dirty work.

I ended up solving the problem without a grammar but as with anything - I could have done it better than the straight procedural code I ended up with.