Different ways of enumeration


Japanese seems to have multiple ways of enumerating sequences. The basic one
is ordinal numbers:

  * Arabic (Indian) numbers like in English: 1,2,3
  * classic Chinese numbers: 一、二、三 etc.
  * special legal numerals: 壱、弍、参 etc.
  * special version of “one”/“first” can be used初号、初版

The “letters”:

  * Latin alphabet (a, b, c, etc.).
  * goujon order (AFAIK usually katakana vowels: ア、イ、ウ、エ、オ); I’ve seen this used in some dictionaries and scientific papers.
  * iroha order (いろはにほへと) - not sure if actually used

Then there are some specialized ones:

  * two-volume book: 上巻、下巻
  * three-volume book: 上巻、中巻、下巻
  * three sizes (S,M,L): 小、中、大 

And something I discovered today:

  * Four-item sequence (ABCD): 甲乙丙丁, apparently originating from the Chinese sexagenary year cycle

Are there any others? What are the situations you would use one over the
other?




I think you have already listed all of the common and not-so-common ones.

  * あ い う
  * ア イ ウ
  * 一 二 三
  * イ ロ ハ (usually katakana)
  * 甲 乙 丙 (explained [here](https://japanese.stackexchange.com/q/1416/5010))
  * 1 2 3 / A B C / a b c / I II III / i ii iii

These letters are often enclosed in parentheses or
[circles](https://japanese.stackexchange.com/a/50519/5010).

イロハ is still widely used in legal documents, dictionaries and such. It's at
least much more common than 甲乙丙. You can check [this "pathological" example of
イロハ順](https://www.mhlw.go.jp/web/t_doc?dataId=84aa9729&dataType=0&pageNo=2);
they used up all the katakana and started to use イイ, イロ and so on!

上(中)下 is only for two- or three-volume books. 天地(人) can be used in a similar
manner
([example](https://ja.wikipedia.org/wiki/%E5%BF%A0%E8%87%A3%E8%94%B5_%E5%A4%A9%E3%81%AE%E5%B7%BB%E3%83%BB%E5%9C%B0%E3%81%AE%E5%B7%BB)),
but it's very rare.




I think you have already listed all of the common and not-so-common ones.

  * あ い う
  * ア イ ウ
  * 一 二 三
  * イ ロ ハ (usually katakana)
  * 甲 乙 丙 (explained [here](https://japanese.stackexchange.com/q/1416/5010))
  * 1 2 3 / A B C / a b c / I II III / i ii iii

These letters are often enclosed in parentheses or
[circles](https://japanese.stackexchange.com/a/50519/5010).

イロハ is still widely used in legal documents, dictionaries and such. It's at
least much more common than 甲乙丙. You can check [this "pathological" example of
イロハ順](https://www.mhlw.go.jp/web/t_doc?dataId=84aa9729&dataType=0&pageNo=2);
they used up all the katakana and started to use イイ, イロ and so on!

上(中)下 is only for two- or three-volume books. 天地(人) can be used in a similar
manner
([example](https://ja.wikipedia.org/wiki/%E5%BF%A0%E8%87%A3%E8%94%B5_%E5%A4%A9%E3%81%AE%E5%B7%BB%E3%83%BB%E5%9C%B0%E3%81%AE%E5%B7%BB)),
but it's very rare.

