Obscure names

[Pavel Baranov]

I'm trying to understand how CGEN works and thanks to CGEN manual
the overall picture is more or less clear. One thing which is not described
in this manual (or I couldn't find the description) is the names like
'src1', 'src2,
'sr', 'dr' in .cpu files in Model/Unit descriptions (for example in
m32r.cpu). I can guess
that these are some kind of register names but I haven't seen list of
possible names
and their descriptions. Can you help me with this information?

Regards,
Pavel