How many letters does the top answer for “a detailed description of design criteria for a piece of work” have?

The most common answer is spec (4 letters).

Crossword clue: a detailed description of design criteria for a piece of work

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

spec 4 letters wn-def

a detailed description of design criteria for a piece of work

specification 13 letters wn-def

a detailed description of design criteria for a piece of work