A contract to refer a present or future legal dispute to arbitration. Such agreements are of two kinds: those referring an existing dispute to arbitration and those relating to disputes that may arise in the future. The second type is much more common. No particular form is necessary, but the agreement should name the place of arbitration and either appoint the arbitrator or arbitrators or (more usually) define the manner in which they are to be appointed in the absence of agreement between the parties. The agreement should also set out the procedure for appointing an umpire if two arbitrators are involved and they fail to agree.