# [OS X TeX] \mathit allowed only in math mode'' error while writing .idx

Herbert Schulz herbs at wideopenwest.com
Mon Feb 10 15:20:38 EST 2020

> On Feb 10, 2020, at 12:35 PM, Murray Eisenberg <murrayeisenberg at gmail.com> wrote:
>
> I’m looking for any possible clues in trying to track down the error with pdflatex
>
>   \mathit allowed only in math mode
>
> encountered while latexmk is writing .idx.
>
> This is occurring, in the first instance with .ind entry
>
> 	\item \idxmark{Urysohn Metrization Theorem}, \hyperpage{506},
> 		\mainref{580}
>
> The function \mainref is defined as:
>
> 	\newcommand{\mainref}[1]{\textbf{\emph{\hyperpage{#1}}}}
>
> But the error occurs even if I change \mainref to: \newcommand{\mainref}[1]{#1}
>
> The document’s .ist file includes
>
> 	item_0  "\n\\item \\idxmark{"
>    	delim_0 "}, "
>
> where \idxmark is defined in my preamble by:
>
> 	\providecommand\gobbleone[1]{}
> 	\newcommand{\idxmark}[1]{{\let\gobbleone\relax\markboth{\sffamily\bfseries#1}{\sffamily\bfseries#1}}#1}
>
> If I comment out the \index entries for that “Urysohn Metrization Theorem”, then the same error occurs for other entries.
>
> I APOLOGIZE for not providing a complete, minimal working example for reproducing the error, but I think some clue might help me devise such. The document in question is of book length, with a complex source structure that includes several style files constituting the preamble.
>
> NOTE: This error did not occur a week or two ago, despite no change to my preamble. So I think something has changed in some latex package to cause this.
> ---
> Murray Eisenberg			murrayeisenberg at gmail.com

Howdy,

What does that entry look like in the source file? Are you using any particular indexing package? Not that I'm on to anything :-(.

Good Luck,

Herb Schulz
(herbs at wideopenwest dot com)