Code of Civil Procedure § 472d
CHAPTER 8. Variance—Mistakes in Pleadings and Amendments
Whenever a demurrer in any action or proceeding is sustained, the court shall include in its decision or order a statement of the specific ground or grounds upon which the decision or order is based which may be by reference to appropriate pages and paragraphs of the demurrer.
The party against whom a demurrer has been sustained may waive these requirements.