Katakana is commonly used to write the Ainu language by Japanese linguists. In Ainu language katakana usage, the consonant that comes at the end of a syllable is represented by a small version of a katakana that corresponds to that final consonant and with an arbitrary vowel. For instance "up" is represented by ウㇷ゚ (ウプ—u followed by small pu). Ainu also requires three additional sounds, represented by セ゜ ([tse]), ツ゜ ([tu̜]) and ト゜ ([tu̜]). In Unicode, the Katakana Phonetic Extensions block (U+31F0–U+31FF)[15] exists for Ainu language support. These characters are used mainly for the Ainu language only:
ㇰ(ク) ㇱ(シ) ㇲ(ス) ㇳ(ト) ㇴ(ヌ) ㇵ(ハ) ㇶ(ヒ) ㇷ(フ)
ㇸ(ヘ) ㇹ(ホ) ㇺ(ム) ㇻ(ラ) ㇼ(リ) ㇽ(ル) ㇾ(レ) ㇿ(ロ)