The full cash value of leasehold estates in exempt property for the production of gas, petroleum and other hydrocarbon substances from beneath the surface of the earth, and all other taxable rights to produce gas, petroleum and other hydrocarbon substances from exempt property (all of which rights are hereinafter in this

section referred to as “such oil and gas interests”), is the value of such oil and gas interests exclusive of the value of any royalties or other rights to share in production from exempt property owned by any tax-exempt entity, whether receivable in money or property and whether measured by or based upon production or income or both. This

section applies to such oil and gas interests created prior to the date on which the decision in De Luz Homes, Inc. v. County of San Diego (1955) 45 Cal. 2d 546, became final. This

section does not, however, apply to any of such oil and gas interests created prior to such date which have been after such date or are hereafter extended or renewed, unless such extension or renewal is pursuant to authority in a contract, lease, statute, regulation, city charter, ordinance, or other source, which authority permits no reduction of the rate of royalty or other right to share in production on grounds of an increase in the assessed valuation of such oil and gas interest. Moreover, this

section does not apply to any of such oil and gas interests if the rate of royalties or other right to share in production has, prior to the effective date of this section, been reduced to adjust for the fact that certain assessors have valued such oil and gas interests without excluding the value of said royalties or other rights to share in production.