- char-upcase charprocedure
- char-downcase charprocedure
- char-foldcase charprocedure
The char-upcase procedure, given an argument that is the lowercase part of a Unicode casing pair, returns the uppercase member of the pair. Note that language-sensitive casing pairs are not used. If the argument is not the lowercase member of such a pair, it is returned.
The char-downcase procedure, given an argument that is the uppercase part of a Unicode casing pair, returns the lowercase member of the pair. Note that language-sensitive casing pairs are not used. If the argument is not the uppercase member of such a pair, it is returned.
The char-foldcase procedure applies the Unicode simple case-folding algorithm to its argument and returns the result. Note that language-sensitive folding is not used. If the character that results from folding is not supported by the implementation, the argument is returned. See UAX #44 (part of the Unicode Standard) for details.
Note that many Unicode lowercase characters do not have uppercase equivalents.