CB-138 has been issued to provide updates to the Standard Valuation Act Valuation Manual that became operative on January 1, 2017, pursuant to Neb. Rev. Stat. § 8908(2) and CB-136.CB-138 has been issued to provide updates to the Standard Valuation Act Valuation Manual that became operative on January 1, 2017, pursuant to Neb. Rev. Stat. § 8908(2) and CB-136.