5.1 Casing

Uppercase and lowercase words do not always apply in multibyte languages. For example, ideographs don't have case. Thus, characters that do not change after a casing function should not be treated as an error when calling an API which returns casing rules.

The following APIs process multibyte characters:

• toupper(): Convert wide characters to uppercase

• tolower(): Convert wide characters to lowercase

• wctype(): Define character class