(soccer) The prohibition of teammates closer to the opponents' goal than the person kicking or throwing the ball unless there are three opponents at least as close to their goal line.

(idiomatic) Examine carefully and thoroughly.

Alternative form of three-revert rule

(Wikimedia jargon) On the English Wikipedia, a rule that states that an editor must not perform more than three reverts on a single page—whether involving the same or different material—within a 24-hour period.

To rule with stern severity.

(law) A legal principle that holds an original copy of a document as superior evidence.

plural of white coat rule

(advertising) A rule prohibiting the use of actors dressed as medical professionals to give a misleading impression of the medical benefits of a product being advertised.

A rule, applied to some controversial debates and discussion panels, stating that anybody who attends is free to use information from the discussion, but cannot reveal who made any comment.

(software engineering) A humorous aphorism stating that the first 90% of the code accounts for the first 90% of the development time, and the remaining 10% of the code accounts for the other 90% of the development time.