Extender

Extender is a character property that identifies letters or symbols which visually extend the shape of a preceding character, often by adding a stroke, tail, or flourish, without carrying independent phonetic value. These characters, such as the Arabic tatweel, the Katakana prolonged sound mark, or the Hawaiian kahakō, are used to alter length, intonation, or to create ligatures and calligraphic effects. Extenders typically do not start words or appear in isolation, and they play a crucial role in scripts like Arabic, Japanese, and Devanagari for proper text shaping and rendering. In text processing, recognizing extenders helps with word boundary detection, line breaking, and search or sorting operations, as they are treated as part of the base character they follow.