20 C.F.R. § 1002.191
As a general rule, the employee is entitled to reemployment in the job position that he or she would have attained with reasonable certainty if not for the absence due to uniformed service. This position is known as the escalator position. The principle behind the escalator position is that, if not for the period of uniformed service, the employee could have been promoted (or, alternatively, demoted, transferred, or laid off) due to intervening events. The escalator principle requires that the employee be reemployed in a position that reflects with reasonable certainty the pay, benefits, seniority, and other job perquisites, that he or she would have attained if not for the period of service. Depending upon the specific circumstances, the employer may have the option, or be required, to reemploy the employee in a position other than the escalator position.
20 C.F.R. § 1002.191