ok, so i checked out the http link that's listed at the top of expr help in pd.

http://www.crca.ucsd.edu/~yadegari/expr.html

and it says,

"Based on original sources from IRCAM's jMax
Released under GNU's General Public License."

so, if it is based on jMax code, does that mean that the original jMax code would also have to be cleared? (it is GPL too)