(a) Basis for Payment.—When practicable, payments under section 4501 of this title shall be made on any of the following bases:

(1) Performance measured by objective, quantifiable methods such as delivery of acceptable items, work measurement, or statistical process controls.

(2) Accomplishment of events defined in the program management plan.

(3) Other quantifiable measures of results.

(b) Payment Amount.—Payments made under section 4501 of this title may not exceed the unpaid contract price.