California Code, Education Code - EDC § 88180

(a) “Differential compensation” means either a reduction in the number of hours required to be actually worked or an increase in salary.

(b) “Shift” means the number of hours worked and shall include a duty-free meal period of not less than one-half hour which, in the case of a seven- or eight-hour shift, shall occur approximately at the midpoint of the shift. This subdivision shall not apply to employees working six hours or less, or assigned to a split shift.