Order, Supreme Court, New York County (Ira Gammerman, J.), entered January 10, 1994, which, inter alia, granted defendants’ motion for summary judgment dismissing the complaint and denied plaintiff’s cross motion for summary judgment, unanimously affirmed, without costs.
We disagree with the IAS Court that the alleged agreement is too indefinite to be enforced, the "industry standards” upon which the modified commission amount was to be based being a sufficiently definite extrinsic standard (see, Cobble Hill Nursing Home v Henry & Warren Corp., 74 NY2d 475, 483) and the other missing terms being determinable from the unmodified written bonus plan. We nevertheless affirm on the alternative ground urged by defendants before the IAS Court (see, Matter *513of American Dental Coop, v Attorney-General of State of N. Y., 127 AD2d 274, 279, n 3) that the alleged oral modification to provide commissions at "industry standards” varies the terms of the written bonus plan, and is inadmissible parol evidence (see, Namad v Salomon Inc., 74 NY2d 751, 752; W.W.W. Assocs. v Giancontieri, 77 NY2d 157, 162) without which plaintiff cannot prove either the existence or terms of the alleged agreement. Concur—Ellerin, J. P., Ross, Williams and Tom, JJ.