When I define multiple terms that contain an underscore and begin with the same string ex_ 1, ex_ 2 (as shown in the example below) I get the following error:

! TeX capacity exceeded, sorry [input stack size=5000]. \expandafter l.30 \end{frame}

However, when I define the term e2 using the commented out line below (e2_ 2) it compiles fine. If I just remove the escaped underscores (see below) that works as well. Can someone tell me how to work around this?


% beamer doesn't define \@idxitem, but it's used by the
% \printterms "index" style, so define it:



% this fails:
 \newterm[label=e1]{ex\_ 1}
 \newterm[label=e2]{ex\_ 2}

% this works
%\newterm[label=e1]{ex\_ 1}
%\newterm[label=e2]{e2\_ 2}

% this works
%\newterm[label=e1]{ex 1}
%\newterm[label=e2]{ex 2}


  • As it says in the documentation, you can't use active characters in the label. Do you really need an underscore in your label? (After all, it's only an identifier not typeset material.) – Nicola Talbot Nov 11 '13 at 17:06
  • I'm a little confused here. In this example: \newterm[label=e1]{ex_ 1} Isn't the label 'e1' and the text/term that contains the active character ('ex\_ 1')? – John Harrold Nov 11 '13 at 19:20
  • 1
    Sorry, I misread your question. I think the problem is the mechanism that sets the default sort value. Try \newterm[label=e1,sort={ex1}]{ex\_ 1} – Nicola Talbot Nov 11 '13 at 19:36
  • That's it, and I think it makes sense as well. Thanks, I appreciate it. – John Harrold Nov 11 '13 at 20:09

The second comment by Nicola Talbot answered my question: Without specifying a sort option it tries to sort by the term and when the sorter gets to the escape character it has a hard time. Specifying the sort option:

\newterm[label=e1,sort={ex1}]{ex\_ 1}
\newterm[label=e2,sort={ex2}]{ex\_ 2}

Solves the problem for me.

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