A witness, other than a designated public employee, may demand a $35 witness fee and mileage at $0.20 a mile, both ways, prior to attending. If not paid, the witness cannot be compelled to attend. If the fees are demanded but not available, the subpoena should be served and the facts noted in the proof of service. Mileage is not paid if the witness is not required to personally attend the hearing. (GC 68093, 68097)