# [Tex/LaTex] Upright subtitle in BibLaTeX

biblatex

I am using BibLaTeX with backend biber and philosopy-modern as style. What I am looking for: I want the subtitles of books, collections etc. in the bibliography to appear in upright font, i.e. not in italics as the maintitle.

Some months ago I found a solution (if I am right I redefined the title in the main document via \renewbibmacro*{title ...}), but inadvertently I now changed some characters and I can't remember how to reestablish my definition. What I had not done was to copy \newbibmacro*{title ...}, redefine it between \makeatletter and \makeatother simly by removing [titlecase] in front of {subtitle} (at least it doesn't work any longer).

Does anybody have any idea?
(I don't attach an example, because the problem remains the same with other biblatex-styles, different biber-options, redefinitions of various parts of the biblatex.def …)

In the following example, I modified the title bibmacro as desired. Note that similar changes should be applied to the booktitle, maintitle, journal, periodical, and issue bibmacros (all located in biblatex.def).

Addendum: The modification is not obvious - it's only a closing brace removed from one code line and added to another. The effect is that \printfield[titlecase]{subtitle} isn't (anymore) part of the argument of \printtext[title].

\documentclass{article}

\usepackage{biblatex}

\renewbibmacro*{title}{%
\ifboolexpr{
test {\iffieldundef{title}}
and
test {\iffieldundef{subtitle}}
}
{}
{\printtext[title]{%
\printfield[titlecase]{title}%
%       \setunit{\subtitlepunct}% DELETED
%       \printfield[titlecase]{subtitle}}% DELETED
\setunit{\subtitlepunct}}% NEW
\printfield[titlecase]{subtitle}% NEW
\newunit}%

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@misc{A01,
author = {Author, A.},
year = {2001},
title = {Alpha},
subtitle = {An introduction},
}
\end{filecontents}