Except where such service is provided by a school district pursuant to Section 44332.5, each county or city and county board of education may provide for the registration of any valid certification or other document authorizing the holder thereof to serve in a position requiring certification qualifications as an employee of the county superintendent of schools of such county or city and county or of a school district under the jurisdiction of such county superintendent of schools. Such registration shall authorize the service of the holder as an employee of the county superintendent of schools or of any school district under his jurisdiction in the capacity in which and for the period of time for which the certification or other document is valid.