# How to prevent upper case in page header?

I just came across this small problem which I can't seem to fix. I have a section which looks like this:

``````\section{Properties of \$C_q\$}
``````

The problem is that the header of the page uses upper case and so it displays this section title as if I had written

``````\section{Properties of \$C_Q\$}
``````

How can I make sure the q is always lower case?

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You could define a macro for this expression:

``````\newcommand{\Cq}{C_q}
``````

and protect it when you use it in such headings:

``````\section{Properties of \$\protect\Cq\$}
``````

`\protect` prevents early expansion of the macro, this way also becoming uppercase is prevented. You may use this macro later in your math expression as well, of course, that's why I did not start math mode inside the macro.

Btw. I would not use all caps headers. In case of fancyhdr, for example, uppercasing can be disabled by `\nouppercase`, such as

``````\rhead{\nouppercase\leftmark}
``````
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