What is De Secta Ad Molendinum?

Legal Definition
Of suit to a mlll. A writ which lay to compel one to continue his custom (of grinding) at a mill. 3 Bl. Comm. 235; Fitzh. Nat Brev. 122, M.
-- Black's Law Dictionary
Legal Definition
A writ to compel one to have his grinding done at the plaintiff’s mill.
-- Ballentine's Law Dictionary