Revenue Recognition We derive revenue from the sale of integrated hardware and software, professional services, maintenance contracts, other services, and third party service contracts. Professional services generally include implementation, installation, and training services. Other services generally include revenue generated through our royalty and extended warranty contracts. We recognize revenue when persuasive evidence of an arrangement exists, delivery of the product or service has occurred, the fee is fixed or determinable and collectability is reasonably assured. We enter into multiple element arrangements as well as standalone sales of product, professional services, and other services. We recognize revenue from standalone product sales upon transfer of title, which is typically upon shipment, provided all other revenue recognition criteria have been met. Revenue generated from standalone professional services and extended warranty contracts is recognized as services are completed, provided all other revenue recognition criteria have been met. In some instances professional service contracts include a customer acceptance provision, in which case revenue is deferred until we have evidence of customer acceptance. We recognize revenue from usage based royalty contracts upon confirmation from the customer of shipment of the system produced pursuant to the royalty agreement. We recognize revenue from multiple element arrangements in accordance with ASC 605-25, Multiple Element Arrangements . We evaluate multiple element arrangements to determine if separate units of accounting exist, and if so, we allocate revenue to each element based upon the relative selling price of each element. ASC 605-25 establishes a hierarchy for determining the amount to allocate to each separate deliverable in an arrangement. We determine selling price using vendor specific objective evidence (VSOE), if it exists; or, if VSOE does not exist, third party evidence (TPE) of fair value if applicable; otherwise, we use the best est