"free for all non-commercial purposes"

http://hgm.nubati.net/cgi-bin/gitweb.cgi?p=xboard.git;a=commitdiff;h=f7f6d954bca7c593d7656edf24a2df177cb06869
https://groups.google.com/forum/#!msg/rec.games.chinese-chess/K2YZ_wCTEm0/EzjeUe8T4BoJ