Proper casing in citation/bibliography titles using biblatex/Biber

Question

My understanding is that bibtex lets the citation style handle capitalization of titles, which is what I would expect from an automated citation tool. Do biblatex and Biber also do this? The document I am working on with these tools seems to be preserving the capitalization in the bib database, which is NOT what I want, and I haven't found any clear references that explain what the expected behavior is.

Answer 1

It might depend on the style and language(s) you are using, but generally titles are printed in the field format titlecase. By default, titlecase has no effect on casing; from biblatex.def:

\DeclareFieldFormat{titlecase}{#1}

If you want all titles in sentence case (i.e. first letter capitalized, the rest in lowercase) you can redefine this format:

\DeclareFieldFormat{titlecase}{\MakeSentenceCase{#1}}

The \MakeSentenceCase command converts its argument to sentence case, except for text enclosed in braces ({}). It also generally has no effect on control sequences. However Latin characters in math ($...$ or \(...\)) are affected and control sequences in $...$ generate parsing errors. To avoid these issues all math can be wrapped in braces. Wrapping a single character in braces affects its kerning, so the biblatex manual recommends wrapping braces around entire words. For example:

title = {An Introduction to {LaTeX}}

instead of:

title = {An Introduction to {L}a{T}e{X}}

You can make casing depend on the entry type(s) by adding an optional argument - for example:

\DeclareFieldFormat[article]{titlecase}{\MakeSentenceCase{#1}}

One catch here is that the titlecase format is rolled out to all titles within an entry type. So in the above example both the title and journaltitle fields would be printed in sentence case. This question addresses how to make title case depend on both the entry and field types.

With babel, casing can also depend on the language. \DeclareCaseLangs specifies all the languages that the starred version \MakeSentenceCase* converts to sentence case. By default we have:

\DeclareCaseLangs{%     
  american,british,canadian,english,australian,newzealand,USenglish,UKenglish}

For further details, see biblatex documentation on the above commands and release notes under the heading "Sentence case vs. title case".