“Roll” means the entire assessment roll. The “secured roll” is that part of the roll containing State assessed property and property the taxes on which are a lien on real property sufficient, in the opinion of the assessor, to secure payment of the taxes. The remainder of the roll is the “unsecured roll.” The “local roll” is those parts of the secured and unsecured roll containing property which it is the county assessor’s duty to assess. The “board roll” is that part of the secured roll containing State assessed property.