Operating nonunitary properties are those that the assessee and its regulatory agency consider to be operating as a unit, but the board considers not part of the unit in the primary function of the assessee. This section does not apply to state-assessed property of regulated railway companies. In the case of regulated railway companies, there shall be only two classifications of property for purposes of this code, unitary and nonunitary.
Ca. Rev. and Tax. Code § 723.1