# Hyperref - Token not allowed [duplicate]

Possible Duplicate:
Hyperref warning - Token not allowed in a PDF string

The following code:

\subsection{The classes $\mathcal{L}(\gamma)$}


generates the errors:

Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing math shift' on input line 1938.

Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing \gamma' on input line 1938.

Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing math shift' on input line 1938.


What do I have to do to keep \gamma in the subsection, so that it is also listed in the table of contents?

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## marked as duplicate by Werner, Jake, Gonzalo Medina, Mico, ThorstenApr 27 '12 at 5:58

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

## 1 Answer

The PDF bookmarks are a different thing than the table of contents. The bookmarks are not typeset by TeX: they simply are strings of characters, so no math or general formatting instructions are allowed.

The easiest method to avoid the warnings is to use \texorpdfstring:

\subsection{The classes \texorpdfstring{$\mathcal{L}(\gamma)$}{Lg}}
`

where in the second argument you put the best approximation possible; after all the bookmarks are only a guide for consulting the document.

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Ahh, I see, those are PDF bookmarks, thanks! –  Chris Apr 26 '12 at 23:14
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