International characters in atoms

I tried GNU Prolog on a Pentium IV PC (I installed it with the downloaded binary) and on an iMac G4 800 (via XGP). In both cases it seems that I cannot use international characters (ASCII codes above 127 or Unicode) in atoms. On the PC certain characters are not even accepted as input from the keyboard. On the mac I can type them in through the XGP interface but the queries don't give any result. Are there plans to allow the use of extended character sets in atoms?

Thanks in advance
Thomas Moraitis