An update of diagxy is now available as ftp.math.mcgill.ca//pub/barr/diagxy.zip. It fixes a couple of serious bugs (in more esoteric shapes), makes some minor improvements in the macros and adds and modifies the documentation, including clarifying the license to make it absolutely clear that there are no restrictions of use. In addition, I have corrected a couple of typos that Steve Bloom found. In addition, I recommend that you download the paper derfun.tex. This is a paper that I wrote last summer (and has been submitted for publication) that I have modified to use the new macros. The bug fixes and modifications were found in getting this paper looking right.