Subring / underring / ring below diacritic in Biblatex

Question

I need to write a "subring", "underring", "combining ring below", "U+0325", whatever you call it, under a letter, in my bibtex document. Usually on Latex I use the package tipa and I just have to use \textsubring{} or \r*{}, but in my .bib file, it does not work anymore. The article I want to cite is :

@article{joseph1982,
  title = {The treatment of \textit{*C\textsubring{R}H-} and the Origin of \textit{CaRa-} in Celtic},
  author = {Joseph, L.},
  date = {1982},
  journaltitle = {Ériu},
  volume = {33},
  pages = {31--57},
  keywords = {celtic}
}

Normally I should get this :

I managed to insert the subring by adding \DeclareUnicodeCharacter{325}{\textsubring{}} in my preambule but it is not perfect since the subring is after the character :

Here is my full latex heading:

\documentclass{report}
\setcounter{tocdepth}{4}
\setcounter{secnumdepth}{4}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[polutonikogreek,french,english]{babel}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{csquotes}
\usepackage[multiple]{footmisc}
\usepackage{tipa}
  \DeclareUnicodeCharacter{325}{\textsubring{}}
\usepackage{supertabular}
\usepackage[
backend=biber,
sorting=nyt,
citestyle=authoryear,
bibstyle=authortitle,
style=authoryear-ibid
]{biblatex}
\addbibresource{Biblio.bib}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhead[C]{}
\fancyhead[R]{}
\fancyhead[L]{\leftmark}

Can you include a sample citation in your Biblio.bib that uses \textsubring? — Werner, Dec 15 '21 at 23:30
I'm a bit confused: you mention bibtex in the title, but in the code you load biblatex with biber back-end. — campa, Dec 16 '21 at 13:31
You can't use combining characters in pdflatex. So inputting U+0325 will not work. — egreg, Dec 17 '21 at 21:49
The modern solution would be to use LuaLaTeX/XeLaTeX and insert the character directly in Unicode as LATIN CAPITAL LETTER R (U+0052) and COMBINING RING BELOW (U+0325) = R̥ — Ingmar, May 17 '22 at 04:50

score 1 · Answer 1 · answered Dec 17 '21 at 22:05

You can call biber with the option

--decodecharsset=null

to disable all conversions into Unicode. The problem is that \textsubring{R} gets translated into R followed by the combining character U+0325, but this can't work in pdflatex that has no way to cope with such characters.

Doing

\DeclareUnicodeCharacter{325}{\textsubring{}}

will do nothing sensible: it will just place the ring after the expected character, as you discovered.

You can call biber with the option

--decodecharsset=null

option, that will disable the conversion to Unicode.

If I do it, I get

      \field{title}{The treatment of \textit{*C\textsubring{R}H-} and the Origin of \textit{CaRa-} in Celtic}

in the generated .bbl file and the output is

Subring / underring / ring below diacritic in Biblatex

1 Answers1