Cal. Gov. Code § 27322.2

A system of microphotography, optical disk, or reproduction by any other technique that does not permit additions, deletions, or changes to the original document may be used by the recorder as a photographic reproduction process to record some or all instruments, papers, and notices that are required or permitted by law to be recorded or filed. All reproductions shall be made in compliance with Section 12168.7. A true copy of the document shall be kept in a safe and separate place that will reasonably assure its preservation for the duration of the retention prescribed by law against loss or destruction. A true copy of the document shall be arranged in a suitable place in the office of the recorder to facilitate public inspection.