13 Pa.C.S. § 2A204 – Formation in general

(a) General rule.— A lease contract may be made in any manner sufficient to show agreement, including conduct by both parties which recognizes the existence of a lease contract.
(b) Effect of undetermined time of making agreement.— An agreement sufficient to constitute a lease contract may be found although the moment of its making is undetermined.
(c) Effect of open terms.— Although one or more terms are left open, a lease contract does not fail for indefiniteness if the parties have intended to make a lease contract and there is a reasonably certain basis for giving an appropriate remedy.