# Using \textunderscore with Biblatex + Biber

I have some bibliography entries whose titles contain underscores, which I am entering as \textunderscore. These compile fine when using plain BibTeX, or when using Biblatex and BibTeX as the backend, but not when using Biblatex with Biber as the backend:

\documentclass{article}
\usepackage[
%backend=bibtex, % this works
backend=biber,  % this doesn't
]{biblatex}

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@inproceedings{pramanick2017jucsenlp,
author       = {Aniket Pramanick and Dipankar Das},
title        = {{JU}{\textunderscore}{CSE}{\textunderscore}{NLP} at
{SemEval}-2017 {Task} 7: Employing Rules to Detect and
Interpret {English} Puns},
booktitle    = {Proceedings of the 11th International Workshop on Semantic
Evaluation (SemEval-2017)},
year         = {2017},
}
\end{filecontents}

\begin{document}
\nocite{*}\printbibliography
\end{document}


Result of running pdflatex:

! Missing $inserted. <inserted text>$
l.23 \end
{document}


Am I doing something wrong or is this a bug in Biblatex and/or Biber? I am using TeX Live 2017 with Biblatex 3.7 and Biber 2.7.

• I would count this as a bug. As a work-around you can use e.g. \bibunderscore in the bib or some other name that biber doesn't know and then in the document \let\bibunderscore\textunderscore. – Ulrike Fischer Aug 16 '17 at 9:32
• Biber's Unicode converter turns \textunderscore into _. And that comes out problematic. You can complain at github.com/plk/biber/issues – moewe Aug 16 '17 at 10:18
• @moewe Done: github.com/plk/biber/issues/180 – Psychonaut Aug 16 '17 at 11:27
• Fixed in biber 2.8 DEV. – PLK Aug 16 '17 at 13:17

You can also enter inline math mode and use:

title        = {{JU}{${\_}$}{CSE}{${\_}$}{NLP} at


If I can take the liberty of turning the comments by Ulrike Fischer, moewe, and PLK into an answer, the behaviour reported in my question was a bug (or at least a questionable design decision) in Biber. It has now been fixed in the development version. It is likely that future stable releases of Biber will gracefully handle instances of \textunderscore in bibliography entries.

For those stuck with a misbehaving version of Biber, the problem can be worked around in various ways:

1. In the .tex document, define a macro that expands to \textunderscore, and then use that macro instead of \textunderscore in the .bib file.

2. In the .tex document, \include the underscore package. Then in the .bib file, use _ instead of \textunderscore.

3. In the .bib file, use $\_$ instead of \textunderscore. (This has the disadvantage of switching to your math font, though it's unlikely that the underscore looks significantly different in it.)

4. Use BibTeX instead of Biber. (This is the only option that doesn't require changing your .bib file. However, it will work only if the file uses BibTeX-compatible syntax, and if your use of Biblatex doesn't rely on Biber-specific features.)