Complex sentence: In Japan, the encoding is heavily used by Unix-derived operating systems such as Linux, but little elsewhere, and is consequently the smallest of the big 3 Japanese encodings behind ISO-2022-JP (JIS) and Shift-JIS.
Split into simpler sentences: In Japan, the encoding is heavily used by Unix or Unix-like operating systems, but seldom used elsewhere. It is consequently the smallest of the big 3 Japanese encodings behind ISO-2022-JP (JIS) and Shift-JIS.