California Code, Government Code - GOV § 27323

The recorder may segregate the instruments, papers, and notices and record them in separate books, or sheets or rolls of film under titles of indices provided for in Article 2 of this chapter.

In lieu thereof the recorder may record any or all of the instruments, papers, or notices in one general series of books or film to be called “official records.” The series shall be numbered consecutively beginning with number one. The recording of instruments, papers, or notices in “official records” imparts notice in like manner and effect as if the instruments, papers, or notices were recorded in separate books or film.

If a system of microphotography is used to record any instruments, papers, or notices, each original roll of film thereof kept by the recorder shall be given a separate number, and shall be called a “book,” “film,” “reel,” or shall be similarly designated, and each page of the instrument, paper, or notice shall be called a “page,” “image” or similar designation. Whenever under any law it is required that an instrument, paper, or notice be identified or referred to as recorded in a book or page or both, it shall be sufficient for purposes of identification and of compliance with that law that reference be made to the instrument, paper, or notice by the designations adopted by the recorder pursuant to the provisions of this section.