Sven, Tor, Michael, Nathan, thanks for all the information. I've tried to synthesize it into something both correct and helpful. The result should show up at http://docs.gimp.org/en/ within a couple of days, in section 2.4.11: maybe you can look it over to see if there's anything I've screwed up. Best, -- Bill ______________ ______________ ______________ ______________ Sent via the KillerWebMail system at primate.ucdavis.edu