In an action to recover damages for breach of a contract to furnish lathing and plastering work, order denying defendant’s motion for leave to serve a supplemental answer reversed, with $10 costs and disbursements, and the motion granted, without costs. The defense-first counterclaim is sufficient as a matter of pleading, and determination of its legal effect will have to await the evidence. Inasmuch as the rules for decision of claims by extrajudicial means are incorporated only by reference in the plastering contract, the binding effect of the rules is to be determined on the knowledge of the parties as to the existence of such rules. (Matter of Level Export Corp. [Wolz, Aiken é Co.], 280 App. Div. 211, 214.) The second counterclaim should have been permitted as an exercise of discretion on the facts and circumstances. (Civ. Prae. Act, § 245-a.) Johnston, Acting P. J., Adel, Wenzel, MaeCrate and Schmidt, JJ., concur.