NCR Corporation employed Mitch Tomlinson for ten years to service and repair ATMs at their locations. He was part of NCR's "cpre workforce." NCR fired him for failing to properly manage time reporting and call management procedures. NCR had issued corporate management policies that stated that its "tactical workforce"- temporary employees- were at-will employees. The policies were silent on the status of the core workforce. Tomlinson argued that since NCR's policies limited at-will employees to the tactical workforce, the core workforce were not at-will employees. Was Tomlinson an at-will employee?