Relating to an exemption from ad valorem taxation by a school district of a dollar amount or a percentage, whichever is greater, of the appraised value of a residence homestead, a reduction of the limitation on the total amount of ad valorem taxes that may be imposed by a school district on the homestead of a person who is elderly or disabled to reflect any increase in the exemption amount, and the protection of school districts against the resulting loss in local revenue.