C15 Use a long dash to separate that main part of the sentence from a long interruption in the middle or a long appositive at the end.
General Principle	Incorrect Example	Correct Example
a) A writer may need to use a long dash to join a long appositive to the end of a sentence.	She had had a narrow escape, an experience she would never forget.  He stepped back and observed the result, a thing of beauty.	She had had a narrow escape – an experience she would never forget.  He stepped back and observed the result – a thing of beauty.
b) A writer may use a long dash to separate the main parts of a sentence from an interruption to that sentence.	If everything material was taken away, electronics, toys, bikes, a child would not exist happily.	If everything material was taken away – electronics, toys, bikes – a child would not exist happily.