Apb

.
Historical Examples

Find the area of triangle APB in terms of x, the side of the square.
The Canterbury Puzzles Henry Ernest Dudeney

abbreviation (in the US)
all-points bulletin
noun

See all-points bulletin

also a.p.b., 1960, police jargon initialism for all-points bulletin, itself attested by 1953 (perhaps more in the jargon of detective novels than in actual police use).
all points bulletin