What’s new in babel 25.10

2026-06-10

Fixes

• A locale in \DocumentMetadata not recognized by babel raised a cryptic error. Now a more meaningful one is shown. See the news page for 25.9 and issue 343. A new locale tag und has been added, whose purpose it to serve as fallback. Currently, there is only an ini file, but more will be added in the near future for several scripts.

• Error with \ShowLocaleProperties with some locales in Unicode engines.

Transliteration of Russian

A transform is provided for the transliteration of Russian using the norm GOST 7.79-2000 System B, named transliteration.gost779b. It requires only ASCII characters and is reversible, which makes it particularly well suited for LaTeX. As explained in the norm (translated from Russian),

The unambiguous reversibility […] is ensured by the specific use of the Latin letters h, y, c and the symbol `. The letters h, y do not represent any Cyrillic letters by themselves and are used only in letter combinations.

Some notes:

• The Cyrillic ‘і’ is entered always as i`.
• The Cyrillic ‘ч’ can be entered as c and cz.
• The characters ‘ь’ and ‘ъ’ are entered as ` or ``, but no provision has been made in the norm to distinguish the case. This transform uppercases them if preceded by a uppercase letter.

You can see the table here (which also includes rules for other Cyrillic languages, not yet implemented).

By applying these principles, you can devise your own (non-standard) extensions For example, ‘ꙋ’ can be u`, and ‘ѡ’ can be o`. They must be prepended to the transform, so:

\babelprehyphenation[prepend, label = transliteration.gost779b]{russian}
  { ([UOuo])` }
  { string = {1|UOuo|ꙊѠꙋѡ} }

Other changes

Tagging PDF Span elements requires horizontal mode. If \DocumentMetadata is used we also force it with \foreignlanguage (it was already done in bidi texts).