(15) SEGMENT AND RELATED INFORMATION We are a major provider of integrated information management solutions and services for the public sector, with a focus on local and state governments. We provide our software systems and services and appraisal services through four business units which focus on the following products: ? financial management and education software solutions; ? financial management and municipal courts software solutions; ? courts and justice software solutions; and ? appraisal and tax software solutions and property appraisal services. In accordance with ASC 280-10, Segment Reporting, the financial management and education software solutions unit, financial management and municipal courts software solutions unit and the courts and justice software solutions unit meet the criteria for aggregation and are presented in one reportable segment, Enterprise Software Solutions ("ESS"). The ESS segment provides municipal and county governments and schools with software systems and services to meet their information technology and automation needs for mission-critical "back-office" functions such as financial management and courts and justice processes. The Appraisal and Tax Software Solutions and Services ("ATSS") segment provides systems and software that automate the appraisal and assessment of real and personal property as well as property appraisal outsourcing services for local governments and taxing authorities. Property appraisal outsourcing services include: the physical inspection of commercial and residential properties; data collection and processing; computer analysis for property valuation; preparation of tax rolls; community education; and arbitration between taxpayers and the assessing jurisdiction. We evaluate performance based on several factors, of which the primary financial measure is business segment operating income. We define segment operating income as income before noncash amortization of intangible assets associated with their acquisition, share-based compensation expense, int