[texhax] A new question not in the TeX FAQ

Jeney Gábor jeneyg at hit.bme.hu
Fri Oct 31 13:24:51 CET 2008

Dear TeXhax,

I am an associate professor at the Budapest University of Technology and
Economics, using (and also teaching) LaTeX, and I have the following
question which I have not been able to find any explanation up to now:

inside the \label statement, it is not possible to use the \usebox
command. It is quite strange, since any other commands can be used
there. I show the code which helped me to discover the problem:

\newenvironment*{tabl}[3]% #1: caption, #2: label, #3: columns

This is just a new environment, which would ease the usage of tabular
inside table environments, e.g.

\begin{tabl}{Wise statements}{wise}{c|r@{,}l}
Expression & \multicolumn{2}{c}{Value} \\
$\pi$ & 3&1415927 \\
$\pi^\pi$ & 36&46216 \\
$\pi^{\pi^\pi}$ & 80662&666

The problem is that ``tabl'' does not work: during compilation, it

! Missing \endcsname inserted.
<to be read again> 
l.15 ... \voidb at x \copy \tabcimke \relax }{{5}{3}}

I have found a workaround though: if I declare a new command which
stores the label and I use this command inside the \label statement, it
works (the .aux file must be deleted, of course):

\newcommand{\tablabel}{} % we will redefine this command later
\newenvironment*{tabl}[3]% #1: caption, #2: label, #3: columns

This works (it compiles smoothly).
But why \usebox does not work inside \label?
Many thanks in advance for your feedback.

Best regards,
                            Gábor JENEY
BME, Dep. of Telecommunications, Mobile Innovation Center |
Office: I.B.116, Tel: +36-1-463-2418, Fax: +36-1-463-3263 |

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