This is the README for diagmac2, Version 2.1 (May 2009)

John Reynolds's diagram macros (available from
http://www.cs.cmu.edu/~jcr/ and at CTAN in macros/latex/contrib/misc)
have been in use since 1987, particularly for commutative diagrams.
Although originally written for use with latex209, they do work with
more recent formats such as latex2e and pdflatex, but the diagmac macros
are based on the original picture environment in LaTeX and inherit its
limitations on line slopes and circle diameters.

diagmac2.sty is a modification of the macros to allow use of the pict2e
package (available at CTAN in macros/latex/contrib) so that there are
effectively no restrictions on line slopes or circle diameters. Starting
in Version 2.1, some extensions have been added. Also, the User's Manual
has been \TeXified (diagmac2.tex) and expanded, including several
examples. The test file (diagmactest.tex) is as originally released by
Reynolds (but modified to load diagmac2.sty).

At Reynolds's ftp site, there is the following disclaimer:

  These macros are in the public domain, and have not changed in many
  years. Acknowledgement of their usage is not necessary. However,
  neither I nor CMU accept any responsibility for the consequences of
  errors in these macros or their documentation. This is more than the
  usual disclaimer; TeX is a beastly language for programming anything
  complex, and I am not an expert in its use, so that there are probably
  errors lurking in the macros.

In fact, after more than 20 years of intensive use by dozens of
enthusiastic users, it seems that not a single error has been
discovered.

The licence for diagmac2.sty and diagmac2.tex is LPPL.

Bob Tennent
School of Computing
Queen's University
Kingston, Canada K7L 3N6
rdt@cs.queensu.ca