Final answer:
A pair of commas is used to set off a proper name within a sentence, providing additional information without interrupting the flow.
Step-by-step explanation:
A pair of commas is used to set off a proper name within a sentence. Commas are used to provide additional information about the proper name without interrupting the flow of the sentence. For example, in the sentence 'The cousins - Tina, Todd, and Sam - arrived at the party together,' the commas are used to set off the names of the cousins within the sentence. This helps to clarify who the cousins are without causing confusion.