# Problem using twocell in xypic

I tried using the \rtwocell command to produce twocells in a commutative diagram and my LaTeX installation (TeX Live on a Mac) does not recognize it. It seems to recognize everything else I have tried with xypic. Are there are known issues with xypic on TeX Live?

This is the example I tried:

\documentclass[11pt]{article}
\usepackage[all,2cell]{xy}
\begin{document}
$\xymatrix{A\rtwocell^f_g{\eta}& B}$
\end{document}


This is the error that is produced

! Undefined control sequence.
<argument> \xyeatall@ \everyentry@ A\rtwocell
^f_g{\eta }
l.4 $\xymatrix{A\rtwocell^f_g{\eta}& B}$

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Please, next time add the code and the error message to the question, rather than in comments. Looking forward for other contributions from you on the site. – egreg May 10 '12 at 14:14

As the manual says in a rather hidden place, you have to say

\UseTwocells


after loading xy (page 44).

\documentclass[11pt]{article}
\usepackage[all,2cell]{xy}
\UseTwocells

\begin{document}
$\xymatrix{A\rtwocell^f_g{\eta}& B}$
\end{document}


There should be a new syntax for two-cells, but unfortunately the manual doesn't describe it.

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Thanks, I did not see that hidden place. Next time I will post the example with the question. Thanks again. – Prakash Panangaden May 10 '12 at 14:29
@PrakashPanangaden It's so well hidden that every time I need to read the manual for finding it. :) – egreg May 10 '12 at 14:36