Cal. Rev. & Tax. Code § 1751

For the purposes of this chapter, the following definitions shall apply:

(a)“Multijurisdictional assessment appeals board” or “board” means a board established by two or more counties pursuant to this chapter meeting as an assessment appeals board on behalf of the participating counties.

(b)“Participating county” means a county that has entered into an agreement, by enactment of an ordinance pursuant to Section 1752.1, to create a multijurisdictional assessment appeals board for the purpose of equalizing the valuation of assessed property.