# Force ibid in citation when using non-standard page numbers

I am using BibLaTeX, and I need to cite a source by its headings, not by its page numbers. Is there any way to force BibLaTeX to use ibid when the title and location are the same?

Note: questions Biblatex: tricks with repeated citations in footnotes and Ibid for citations with same title and page do not address this issue. I specifically need to cite using something other than the simple page number.

As far as I can see, I have used the correct package options (e.g., ibidpage=true). Here is the minimum working example:

\documentclass{book}

\usepackage
[backend=biber,
style=verbose-ibid,
citepages=omit,
ibidpage=true,
firstinits=true]
{biblatex}

\usepackage{filecontents}

\begin{filecontents}{ibid.bib}

@book{a,
title    = {Summa theologiae},
author   = {{Thomas Aquinas}},
}

\end{filecontents}

\begin{document}

Here is some reference.\footcite[2]{a}
Here is some reference.\footcite[2]{a}
Here is some reference.\footcite[I, q.~1, a.~4]{a}
Here is some reference.\footcite[I, q.~1, a.~4]{a}
\printbibliography

\end{document}


The footnotes I get for the first two, which use a standard page number are

1 Thomas Aquinas. Summa theologiae, p. 2.
2 Ibid.

as expected. However, the other two, which uses the headings, produces

3 Ibid., I, q. 1, a. 4.
4 Ibid., I, q. 1, a. 4.

The desired output for the fourth footnote is simply

4 Ibid.

Can this be done?

• Try loccittracker=context. The ibidpage option implicitly sets loccittracker=constrict. See pp. 55 sq. of the biblatex documentation, the constrict explanation states "In addition to that, this mode also checks if the postnote argument is numerical [...]." – moewe Apr 25 '14 at 19:18
• Yes, that worked perfectly. If you would like to receive a check mark, submit an answer. – AthanasiusOfAlex Apr 26 '14 at 7:39

The ibidpage option in verbose-ibid sets loccittracker=constrict implicitly (see verbose-ibid.cbx). loccittracker=strict will not only distinguish footnote and body citations and suppress potentially ambiguous situations, it will also "check[...] if the postnote argument is numerical (based on \ifnumerals [...])." (pp. 60 sq. of the biblatex documentation).

That means that

Here is some reference.\footcite[2]{cicero}
Here is some reference.\footcite[2]{cicero}


is recognised as the same postnote because it is the same postnote in both cases and the postnote is numeric. But

Here is some reference.\footcite[I, q.~1, a.~4]{cicero}
Here is some reference.\footcite[I, q.~1, a.~4]{cicero}


does not pass the test even though the two postnotes are identical because they are not numeric as tested by \ifnumerals.

We can override this behaviour explicitly with loccittracker=context. With that option biblatex does not consider the outcome of the \ifnumerals test when checking for matching postnotes.

\documentclass{book}
\usepackage[backend=biber, style=verbose-ibid, citepages=omit,
ibidpage=true, firstinits=true, loccittracker=context]{biblatex}