Punctuation vowel of the word. Arabic, Urdu, and Persian—written from right to left—use a reversed question mark: , and a reversed comma: . This is a modern innovation; pre-modern Arabic did not use punctuation. Hebrew, which is also written from right to left, uses the same characters as in English, and . Originally, Sanskrit had no punctuation. In the 17th century, Sanskrit and Marathi, both written using Devanagari, started using the vertical bar to end a line of prose and double vertical bars in verse. Punctuation was not used in Chinese, Japanese, and Korean writing until the adoption of punctuation from
Comma category by Lawvere, which involved the comma punctuation mark. Although standard notation has changed, since the use of a comma as an operator is potentially confusing, and even Lawvere dislikes the uninformative term "comma category" (Lawvere, 1963 p. 13), the name persists. The most general comma category construction involves two functors with the same codomain. Often one of these will have domain 1 (the one-object one-morphism category). Some accounts of category theory consider only these special cases, but the term comma category is actually much more general. Suppose that formula_1, formula_2, and formula_3 are categories, and formula_4 and formula_5 (for source