Gojūon
In the Japanese language, the 五十音 is a traditional system ordering kana characters by their component phonemes, roughly analogous to alphabetical order. The "fifty" (gojū) in its name refers to the 5×10 grid in which the characters are displayed. Each kana, which may be a hiragana or katakana character, corresponds to one sound in Japanese. As depicted at the right using hiragana characters, the sequence begins with あ (a), い (i), う (u), え (e), お (o), then continues with か (ka), き (ki), く (ku), け (ke), こ (ko), and so on and so forth for a total of ten rows of five columns. Although nominally containing 50 characters, the grid is not completely filled, and, further, there is an extra character added outside the grid at the end: with 5 gaps and 1 extra character, the current number of distinct kana in a syllabic chart in modern Japanese is therefore 46. Some of these gaps have always existed as gaps in sound: there was no yi or wu even in Old Japanese, with the kana for i and u doubling up for those phantom values. Ye persisted long enough for kana to be developed for it, but disappeared in Early Middle Japanese, having merged with e. Much later, with the spelling reforms after World War II, the kana for wi and we were replaced with i and e, the sounds they had merged with. The kana for syllabic n (hiragana ん) is not part of the grid, as it was introduced long after the gojūon ordering was devised. (Previously mu (hiragana む) was used for this sound.) The gojūon contains all the basic kana, but it does not include: versions of kana with a dakuten such as が (ga) or だ (da), or kana with handakuten such as ぱ (pa) or ぷ (pu), smaller kana (sutegana), such as the sokuon (っ) or in the yōon (ゃ,ゅ,ょ). The gojūon order is the prevalent system for collating Japanese in Japan. For example, dictionaries are ordered using this method. Other systems used are the iroha ordering, and, for kanji, the radical ordering. The gojūon arrangement is thought to have been influenced by both the Siddham script used for writing Sanskrit and the Chinese fanqie system.