Consider the following
\documentclass{article}
\usepackage{xymtex}
%\usepackage[chemist]{chemtimes}
\begin{document}
\tetrahedral{0==A;1==B;2==C;3==D;4==E}
\end{document}
It's very simple and it pdf-compiles on my linux box (ubuntu 10.04, texlive 2009)
Now consider this similar code
\documentclass{article}
\usepackage{xymtex}
%\usepackage[chemist]{chemtimes}
%\usepackage{aliphat}
\begin{document}
\square{0==A;1==B;2==C;3==D;4==E}
\end{document}
On pdf and dvi compiling this last code I get the following error
ERROR: Undefined control sequence.
--- TeX said --- l.6 \square {0==A;1==B;2==C;3==D;4==E} --- HELP --- TeX encountered an unknown command name. .....
Uncommenting the two \usepackage lines do not solve the problem.
Any idea ??
\squarehas been replaced by\squareplanarto avoid conflicts. Somehow this didn't get into the documentation. – egreg Mar 17 at 17:01