Uniquely identifying

A clue is uniquely identifying if and only if the text of the clue refers to exactly one potential answer.

Ideally, every sentence in a good tossup will contain at least one uniquely identifying clause, and all such clauses will be about the actual answer to the tossup; a clue for which this is not the case is known as a hose. There is more flexibility to use non-unique sentences in bonus parts, but each bonus part should contain at least one uniquely identifying clue.

Other trivia events sometimes refer to this property as "pinned", or refer to adding information that makes an otherwise non-unique clue unique as adding "the pin"; that may be because those were the terms of art among writers for game shows such as Who Wants To Be A Millionaire? as recently as the mid-2000s [1].