For apportionment purposes, attendance of a pupil upon schools or classes maintained by a school district or a county superintendent may be counted when the pupil is present during the time lawfully prescribed for the school or class in which he is enrolled and when such attendance meets the requirements prescribed by Education Code Section 46300. In addition, if the pupil is enrolled in summer school his attendance may be counted only if the summer school meets the requirements of Education Code Section 12400.
Cal. Code Regs. Tit. 5, § 402