* Mostly compatible with makeindex and upper compatible with mendex, based on mendex version 2.6f by ASCII media works.
* Unicode for internal process and support UTF-8 encoding for input/output. Work with upLaTeX, XeLaTeX and luaLaTeX.
* Support Latin (including non-English), Greek, Cyrillic, Korean Hangul and Chinese Han (Hanzi ideographs) scripts as well as Japanese Kana.
* Support Devanagari, Thai, Arabic and Hebrew scripts (experimental).
* Support four kinds of sort orders (Pinyin, Radical-Stroke, Stroke and Zhuyin) for Chinese Han scripts (Hanzi ideographs).
* Apply International Components for Unicode (ICU) for sorting process.