Does a change of plea form need to be signed in open court?

Defendant signed a change-of-plea form and entered his plea in open court. Defendant was advised of his constitutional rights, and the court conducted a thorough plea inquiry. Defendant responded rationally to all inquiries. No one, neither the trial judge, nor the prosecutor, nor defense counsel, nor defendant himself, gave any indication that defendant was anything other than fully cognizant of his actions and statements in making his plea. (People v. Ravaux (2006) 142 Cal.App.4th 914, 917-918.)