JIS X 0208 is a Japanese Industrial Standard defining a set of kanji indexed by a pair of integers from 1 to 94 (this is known as the kuten pair of the kanji). This standard was previously known as JIS-C-6226.
The standard defines two "levels" of kanji. Level 1 contains 2965 characters of the most common [kanji] (arranged by their [on yomi] - Chinese style - pronunciation), and level 2 contains 3390 characaters the next most common kanji (arranged in dictionary order after the level 1 characters). Also encoded are katakana, hiragana, romaji (Latin characters, but "full width"), Greek, Cyrillic, line drawing characters and various symbols.
JIS X 0208 is incorporated into many Japanese encodings, such as Shift_JIS, EUC-JP and ISO 2022-JP .
Japanese software typically uses "shift JIS order" (actually this means the JIS X 0208 order described above) to sort kanji for display to the user.