How do you disable en and em dash ligatures in a biblatex/biber bibliography?

Question

I am trying to write an MLA conforming paper with LaTeX for a school assignment, but I have a very strict professor when it comes to bibliography formatting. Specifically, my issue is that BibLaTeX/Biber appears to be printing three connected dashes when listing two works by the same author, which causes them to look like one long dash instead of three separate ones. I am guessing that this is a ligature feature that runs automatically inside \printbibliography, but when I tried calling \usepackage{microtype} and \DisableLigatures{} in the preamble, it only affected dashes outside of the bibliography.

If possible, I would like to only disable this en/em dash feature inside the \printbibliography command.

Here is what I am currently getting: And here is what is shown on the MLA website:

Here's a simple example:

• Test.tex:

\documentclass[12pt]{article}
% Mla and bibliography support.
\usepackage[american]{babel}
\usepackage{csquotes}
\usepackage{ifpdf}
\usepackage{mla}
\usepackage[style=mla-new,backend=biber]{biblatex}
% Add bibliography here.
\addbibresource{Test.bib}
\defbibheading{bibliography}{\center Works Cited}
\begin{document}
\begin{mla}{First Name}{Last Name}{Professor}{Course Name}{\today}{Title}
    Sentence 1 \autocite{the_editors_of_encyclopaedia_britannica_henry_2023}.
    Sentence 2 \autocite{the_editors_of_encyclopaedia_britannica_mexican-american_2023}.
\newpage
\printbibliography


\end{mla}
\end{document}

• Test.bib

@inreference{the_editors_of_encyclopaedia_britannica_henry_2023,
    title = {Henry David Thoreau},
    url = {https://www.britannica.com/biography/Henry-David-Thoreau},
    abstract = {Henry David Thoreau, American essayist, poet, and practical philosopher renowned for having lived the doctrines of Transcendentalism as recorded in his masterwork, Walden (1854), and for having been a vigorous advocate of civil liberties, as evidenced in the essay ‘Civil Disobedience’ (1849).},
    booktitle = {Encyclopedia Britannica},
    author = {{The Editors of Encyclopaedia Britannica}},
    date = {2023-07-08},
    langid = {english},
    file = {Snapshot:/home/cachandler/Productivity/Zotero/storage/I2SMT29Q/Henry-David-Thoreau.html:text/html},
}
@inreference{the_editors_of_encyclopaedia_britannica_mexican-american_2023,
    title = {Mexican-American War},
    url = {https://www.britannica.com/event/Mexican-American-War},
    abstract = {Mexican-American War, war between the U.S. and Mexico from 1846 to 1848. It was caused by a territorial dispute stemming from the United States’ annexation of Texas in 1845 and from contention over whether Texas ended at the Nueces River or the Rio Grande.},
    booktitle = {Encyclopedia Britannica},
    author = {{The Editors of Encyclopaedia Britannica}},
    date = {2023-06-19},
    langid = {english},
    file = {Snapshot:/home/cachandler/Productivity/Zotero/storage/R4S2NAND/Mexican-American-War.html:text/html},
}

Answer 1

You may be interested in the longdash option of biblatex-mla. The documentation explains

The 9th edition of the MLA Handbook clarifies that dashes indicating multiple entries by one author can either be styled with three em-dashes or three hyphens. From version 2.0, output defaults to em-dashes, but setting longdash to false reverts back to hyphens:

\usepackage[style=mla,longdash=false]{biblatex}

So you may want to try

\documentclass[12pt]{article}
\usepackage[american]{babel}
\usepackage{csquotes}
\usepackage{ifpdf}
\usepackage{mla}
\usepackage[style=mla-new,backend=biber,longdash=false]{biblatex}
\begin{filecontents}{\jobname.bib}
@inreference{the_editors_of_encyclopaedia_britannica_henry_2023,
    title = {Henry David Thoreau},
    url = {https://www.britannica.com/biography/Henry-David-Thoreau},
    abstract = {Henry David Thoreau, American essayist, poet, and practical philosopher renowned for having lived the doctrines of Transcendentalism as recorded in his masterwork, Walden (1854), and for having been a vigorous advocate of civil liberties, as evidenced in the essay ‘Civil Disobedience’ (1849).},
    booktitle = {Encyclopedia Britannica},
    author = {{The Editors of Encyclopaedia Britannica}},
    date = {2023-07-08},
    langid = {english},
    file = {Snapshot:/home/cachandler/Productivity/Zotero/storage/I2SMT29Q/Henry-David-Thoreau.html:text/html},
}
@inreference{the_editors_of_encyclopaedia_britannica_mexican-american_2023,
    title = {Mexican-American War},
    url = {https://www.britannica.com/event/Mexican-American-War},
    abstract = {Mexican-American War, war between the U.S. and Mexico from 1846 to 1848. It was caused by a territorial dispute stemming from the United States’ annexation of Texas in 1845 and from contention over whether Texas ended at the Nueces River or the Rio Grande.},
    booktitle = {Encyclopedia Britannica},
    author = {{The Editors of Encyclopaedia Britannica}},
    date = {2023-06-19},
    langid = {english},
    file = {Snapshot:/home/cachandler/Productivity/Zotero/storage/R4S2NAND/Mexican-American-War.html:text/html},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\defbibheading{bibliography}{\center Works Cited}
\begin{document}
\begin{mla}{First Name}{Last Name}{Professor}{Course Name}{\today}{Title}
    Sentence 1 \autocite{the_editors_of_encyclopaedia_britannica_henry_2023}.
    Sentence 2 \autocite{the_editors_of_encyclopaedia_britannica_mexican-american_2023}.
\newpage
\printbibliography


\end{mla}
\end{document}

---

If you prefer em-dashes with spaces between them try

\renewcommand*{\mlanamedash}{\textemdash\kern 1pt\textemdash\kern 1pt\textemdash}
\renewcommand*{\bibnamedash}{%
  \printtext[noformat]{\mlanamedash}
  \iffieldundef{nameaddon}%
    {\setunit{\addperiod\addspace}}%
    {\setunit{\nopunct}}}%

I had to add a non-negative kern to get spaces between them, but I suspect that if and the extent to which this is necessary depends also on the font you use, so you might want to play around with the \kern 1pt here.