Serial comma toast. Adding a serial comma removes this ambiguity. Writers who normally avoid the serial comma often use one in these circumstances, although sometimes re-ordering the elements of such a list can help as well. In some circumstances using the serial comma can create ambiguity. If the book dedication above is changed to the serial comma after "Ayn Rand" creates ambiguity about the writer's mother because it uses punctuation identical to that used for an appositive phrase, leaving it unclear whether this is a list of three entities (1, my mother; 2, Ayn Rand; and 3, God) or of only two
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