A type of lease in general use; the other common type is the or lease (q.v.), There is no single form of the unless lease, but it is known as the unless lease because of the wording of the delay rental clause (q.v.) Which usually takes the following form "if no well is commenced on said land on or before the date hereof, this lease shall terminate as to both parties unless the Lessee on or before that date shall pay or tender to lessor the sum of--- Dollars ($-----) which shall operate as rental and cover the privilege of deferring the commencement of a well for 12 months from said date."
