20 C.F.R. § 1002.192
In all cases, the starting point for determining the proper reemployment position is the escalator position, which is the job position that the employee would have attained if his or her continuous employment had not been interrupted due to uniformed service. Once this position is determined, the employer may have to consider several factors before determining the appropriate reemployment position in any particular case. Such factors may include the employee's length of service, qualifications, and disability, if any. The reemployment position may be either the escalator position; the pre-service position; a position comparable to the escalator or pre-service position; or, the nearest approximation to one of these positions.
20 C.F.R. § 1002.192