Comma the purpose of the comma. There are also a number of comma-like diacritics with "COMMA" in their Unicode names. These do not serve a punctuation function. A comma-like low quotation mark is also available (shown below; raised single quotation marks are not shown). Various other Unicode characters combine commas or comma-like figures with other characters, and are not shown here. In the 3rd century BC, Aristophanes of Byzantium invented a system of single dots ("distinctiones") that separated verses (colometry) and indicated the amount of breath needed to complete each fragment of the text when reading aloud. The different lengths were
That that is is that that is not is not is that it it is That that is is that that is not is not is that it it is That that is is that that is not is not is that it it is is an English word sequence demonstrating syntactic ambiguity. It is used as an example illustrating the importance of proper punctuation. The sequence can be understood as any of four grammatically-correct sequences, each with at least four discrete sentences, by adding punctuation: The first two relate a simple philosophical proverb in the style of Parmenides that all that is, is, and that anything that does not exist does not. The phrase