Revenue Recognition Revenues are generated principally through admissions and concessions sales with proceeds received in cash or via credit card at the point of sale. Other operating revenues consist primarily of product advertising (including vendor marketing programs) and other ancillary revenues that are recognized as income in the period earned. The Company generally recognizes payments received attributable to the marketing and advertising services provided by the Company under certain vendor programs as revenue in the periods in which the advertising is displayed or when the related impressions are delivered. Such impressions are measured by the concession product sales volume, which is a mutually agreed upon proxy of attendance and reflects the Company's marketing and advertising services delivered to its vendors. In instances where the consideration received is in excess of fair value of the advertising services provided, the excess is recorded as a reduction of concession costs. The Company maintains a deferred revenue balance pertaining to cash received from the sale of discount tickets and gift cards that have not been redeemed. The Company recognizes revenue associated with discount tickets and gift cards when redeemed, or when the likelihood of redemption becomes remote. The determination of the likelihood of redemption is based on an analysis of historical redemption trends. Amortization of deferred revenue related to the amount we received for agreeing to the existing National CineMedia exhibitor services agreement modification and amounts recorded in connection with the receipt of newly issued common units of National CineMedia pursuant to the provisions of the Common Unit Adjustment Agreement are described below in this Note 2 under "Deferred Revenue" and in Note 4 "Investments."