UPCS

Set to 4 different clues across 4 published puzzles, most often “Food pkg. markings” — The New York Times, Wednesday, 20 February 2008.

4 letters

Every clue on record, most used first

Food pkg. markingsonce
The New York Times — Wednesday, 20 February 2008
Proofs of purchase, often: Abbr.once
The New York Times — Saturday, 30 June 2007
Short lines at a store: Abbr.once
The New York Times — Saturday, 25 December 2004
They come in bars: Abbr.once
The New York Times — Monday, 11 June 2001