Government employees appointed following a regular competitive selection procedure and statutory rules must rank senior in the cadre to those who entered service as temporary, ad hoc, stopgap measures, or through emergency provisions. Temporary or ad hoc appointees (such as those under Rule 10(a)(i)) cannot claim seniority in the cadre on the basis of their continuous temporary service prior to formal regularisation. Regular direct recruits possess a legitimate expectation that their inter se seniority will not be demoted by the retrospective regularisation of temporary or back-door appointees.