What is 4000a VC of the California Vehicle code?

4000a VC: Speed Limit. The speed limit shall not exceed 25 mph in an alley or on any roadway serving any school having an average daily attendance of 25,000 or more students, or on the grounds of a public school having an average daily attendance of 25,000 or more students, regardless of whether such roadway or grounds are within a business or residential district.