Cal. Educ. Code § 44894
(b) If an employee is authorized to render service in more than one type of position for which certification qualifications are required, either by virtue of his possession of one certification document authorizing service in two or more of such positions, or by virtue of his possession of separate certification documents authorizing service in two or more such positions, or any combination thereof, he shall, upon satisfying all other requirements prescribed by law, acquire permanent status as follows: