Philippe Verdy wrote:
It is not proper to encode English, French, ..., text that is eventually rendered using small capital glyphs using the characters U+1D00 á LATIN LETTER SMALL CAPITAL A and friends. One should use the "regular" letters, either uppercase (e.g. in acronyms and such) or lowercase (e.g. at the beginning of chapter) as appropriate. One way to choose between uppercase and lowercase is to consider what happens if only the uppercase and lowercase glyphs are available. The fact that those character occurrences are intended to be rendered using small cap glyphs does not change their identity.The most common use I have seen of small capitals is as a font style, where they were used to represent lowercase letters (the uppercase letters being presented with full-height style).
Conversely, the identity of the LATIN LETTER SMALL CAPITAL characters is closely connected to IPA, UPA and, more generally, phonetic texts.
This is what TUS 4.0 is saying page 171, under "Typographic variants".
Eric.
