Uppercase

Uppercase is a binary character property that identifies letters with a distinct uppercase form, such as Latin 'A' or Greek 'Σ', used primarily for capitalization in writing systems. This classification is derived from the character's primary alphabetic status and its case mapping, which defines a one-to-one correspondence to a lowercase counterpart. Not all letters have an uppercase variant, like those in scripts without case distinction, such as Arabic or Hebrew, and some characters may be uppercase in one context but not in another, like titlecase letters. The property also includes uppercase forms of letters that are not part of the standard A-Z range, covering accented characters, ligatures, and letters from other scripts. Its main purpose is to enable text processing functions like case conversion, sorting, and searching, ensuring predictable behavior when converting text to lowercase or checking for capitalization.