What is Affirmative Statute?

Legal Definition
In legislation. A statute couched in affirmative or mandatory terms; one which directs the doing of an act, or declares what shall be done ; as a negative statute is one which prohibits a thing from being done, or declares what shall not be done. Blackstone describes affirmative acts of parliament as those "wherein justice is directed to be done according to the law of the land." 1 Bl. Comm. 142.
-- Black's Law Dictionary