5 C.F.R. § 316.901
In accordance with the provisions of this section, an agency may make a time-limited appointment of an eligible and qualified post-secondary student, to any position in the competitive service, at the General Schedule (GS) 11 level or below (or equivalent), without regard to the provisions of 5 U.S.C. 3309 through 3319 and 3330 . An agency may appoint an individual for an initial period not to exceed 1 year, or for an initial period expected to last more than 1 year but less than 4 years, in accordance with §§ 316.401(c)(1) and 316.301(a) and (b) , respectively, to coincide with the individual's academic curriculum. In either case an agency may extend or seek extension from OPM, as appropriate in accordance with this part, of an initial appointment for a period that will allow the post-secondary student to complete his or her academic requirements leading to the awarding of a degree or certificate, as appropriate.
5 C.F.R. §316.901