2009 California Code of Civil Procedure - Section 2064-2065 :: Title 5. Of The Rights And Duties Of Witnesses

2064.  A witness, served with a subpoena, must attend at the time
appointed, with any papers under his control lawfully required by the
subpoena, and answer all pertinent and legal questions; and, unless
sooner discharged, must remain until the testimony is closed.

2065.  Any witness who is subpoenaed in any civil or administrative
action or proceeding shall be given written notice on the subpoena
that the witness may be entitled to receive fees and mileage. Such
notice shall indicate generally the manner in which the request for
fees and mileage should be made.