The CTYPE category

The CTYPE category defines how to classify the characters of the code set that the locale supports.

This category includes specifications for which characters the locale classifies as spaces, blanks, control characters, digits, uppercase letters, lowercase letters, and punctuation symbols.

This category might also include mappings between uppercase and lowercase letters. HCL OneDB™ products access this category when they need to determine the validity of an identifier name, to shift the letter case of a character, or to compare characters.