Punctuation two styles differ mainly in the way in which they handle quotation marks, particularly in conjunction with other punctuation marks. In British English, punctuation such as periods and commas are placed outside the closing quotation mark; in American English, however, punctuation is placed inside the closing quotation mark. This rule varies for other punctuation marks; for example, American English follows the British English rule when it comes to semicolons, colons, question marks, and exclamation points. Other languages of Europe use much the same punctuation as English. The similarity is so strong that the few variations may confuse a native English
That that is is that that is not is not is that it it is was noted in "Brewer's Dictionary of Phrase and Fable". This phrase appeared in the 1968 American movie "Charly", written to demonstrate punctuation to the main character Charly's teacher, in a scene to demonstrate that the surgical operation to make the character smarter had succeeded. 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