# What are hyperref’s PDF bookmarks and how do I use them?

I have very often met the Package hyperref Warning: Token not allowed in a PDF string. Being fed up about it and curious to know what it meant, I was about to ask the n-th duplicate of that questions. Fortunately I bumped into this question just in time and solved the problem. Another question was naturally opened in the process: what are these pdf bookmarks, what is their use, and how do I make them appear in the pdf? And since I had a \cdot in a section title, is it possible to have a high dot in a bookmark, as \texttwosuperior seems to make it possible for a 2?

• A pdf bookmark is basically the same thing in a .pdf file as a piece of paper (or whatever) positioned between pages of a real book: It lets you easily find some portions of content (say a figure,table,chapter, section etc.) from the bookmark view in your reader. You can add basically anywhere a bookmark with a comment like \pdfbookmark ...
– user31729
Apr 22, 2014 at 14:39
• @MickG If you use either \usepackage[utf8]{inputenc} OR xelatex, you can just place the unicode char for \cdot in the text, which is U+00B7 or as a copy-paste template · Apr 22, 2014 at 15:21

Examples, how to generate the dots (middle and above):

\documentclass{article}

\usepackage[
pdfencoding=auto, % or option "unicode"
psdextra, % additional math macros are supported in bookmarks
]{hyperref}[2012/08/13]% psdextra is a quite new feature
\usepackage{bookmark}% recommended

\begin{document}
\section{middle dot: $\cdot$}
\section{U+00B7: \texorpdfstring{$\cdot$}{\unichar{"00B7}}}
\section{dot above: \texorpdfstring{\.{}}{\textdotaccent}}
\section{U+02D9: \texorpdfstring{\.{}}{\unichar{"02D9}}}
\end{document}


The first \section generates warnings because of $ characters: Package hyperref Warning: Token not allowed in a PDF string (Unicode): (hyperref) removing math shift' on input line 10.  Either they can be ignored or they can be avoided by: • \section{middle dot: \ensuremath{\cdot}} • \section{middle dot: \texorpdfstring{$\cdot\$}{\cdot}}`