:legal: adj. Loosely used to mean `in accordance with all the
relevant rules', esp. in connection with some set of constraints
defined by software. "The older =+ alternate for += is no longer
legal syntax in ANSI C." "This parser processes each line of
legal input the moment it sees the trailing linefeed." Hackers
often model their work as a sort of game played with the
environment in which the objective is to maneuver through the
thicket of `natural laws' to achieve a desired objective. Their
use of `legal' is flavored as much by this game-playing sense as by
the more conventional one having to do with courts and lawyers.
Compare {language lawyer}, {legalese}.
-- The AI Hackers Dictionary