PicTeX is a set of macros by Michael Wichura for drawing diagrams
and pictures. The
macros are freely available; however, the
PicTeX manual itself is not free.
Unfortunately, TUG is no longer able to supply copies of the
manual (as it once did), and it is now available only through Personal
TeX Inc, the vendors of PCTeX (
http://www.pctex.com/). The
manual is
not available electronically.
However, there
is a summary of PicTeX commands available on
CTAN, which is a great aide-memoire for those who basically
know the package to start with.
This is FAQ version 3.27, released on 2013-06-07.