In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This ASU is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. We adopted this ASU on January 1, 2018 retrospectively, with the cumulative effect of initial application (which was zero) recognized in retained earnings on that date. Revenue from product sales and supplies is generally recorded when we ship the product and title has passed to the customer, provided that we have evidence of a customer arrangement and can conclude that collection is probable. The prices at which we sell our products are fixed and determinable at the time we accept a customer's order. We recognize revenue from sales to stocking distributors when there is no right of return, other than for normal warranty claims, and generally have no ongoing obligations related to product sales, except for normal warranty. Revenue from training course licenses is recognized as revenue at the time of sale. Training and certification revenues are recognized the day the training and certification occurs. Data recording revenue is recognized based on each day's usage of enrolled devices. Revenues arising from extended warranty contracts are booked as sales over their life on a straight-line basis. We are providing for customer financing and leasing, which we recognize as revenue over the applicable lease term. Occasionally, we rent used equipment to customers, and in those cases, we recognize the revenues as they are earned over the life of the contract. Revenues from rental of equipment and extended service plans are recognized over the life of the contracts. Royalty income is recognized in accordance with agreed upon terms, when performance obligations are satisfied, the amount is fixed or determinable and collectability is reasonably assured. Rental income from space leased to our tenants is recognized in the month in which it is due, which approximates if it were recognized on a straight-line basis over the term of the related lease. On occasion we receive customer deposits for future product orders. Customer deposits are initially recorded as a liability and recognized as revenue when the product is shipped and title has passed to the customer. Topic 606 requires the disaggregation of revenue into broad categories, which we have defined as shown below for the three months ended March 31, 2019 and March 31, 2018. Product sales: 2019 2018 Product sales and supplies $ 1,800,783 $ 1,935,006 Training, certification and data recording 146,496 157,741 Service plans and equipment rental 22,822 29,496 Products subtotal 1,970,101 2,122,243 Royalties 72,838 65,065 Building rentals 25,822 14,601 Total revenues $ 2,068,761 $ 2,201,909