California Code, Code of Civil Procedure - CCP § 571

If a referee or commissioner is appointed by a court and the duties ofthe referee or commissioner will, or are reasonably anticipated to, involve the custody of personal property or the receipt or disbursement of moneys, the order of appointment shall provide that before entering uponthe duties,the referee or commissionershall execute an undertaking to the State of California, to the effect thatthe referee or commissioner will faithfully discharge the duties of referee or commissioner, as the case may be, and obey the orders of the court therein. The order of appointment shall specify the amount of the undertaking, but a failure to so specify shall not invalidate the order.