CAL. CCP. CODE § 94 : California Code - Section 94

Discovery is permitted only to the extent provided by this section and Section 95. This discovery shall comply with the notice and format requirements of the particular method of discovery, as provided in Title 4 (commencing with Section 2016.010) of Part 4. As to each adverse party, a party may use the following forms of discovery:

(a) Any combination of 35 of the following:

(1) Interrogatories (with no subparts) under Chapter 13 (commencing with Section 2030.010) of Title 4 of Part 4.

(2) Demands to produce documents or things under Chapter 14 (commencing with Section 2031.010) of Title 4 of Part 4.

(3) Requests for admission (with no subparts) under Chapter 16 (commencing with Section 2033.010) of Title 4 of Part 4.

(b) One oral or written deposition under Chapter 9 (commencing with Section 2025.010), Chapter 10 (commencing with Section 2026.010), or Chapter 11 (commencing with Section 2028.010) of Title 4 of Part 4. For purposes of this subdivision, a deposition of an organization shall be treated as a single deposition even though more than one person may be designated or required to testify pursuant to Section 2025.230.

(c) Any party may serve on any person a deposition subpoena duces tecum requiring the person served to mail copies of documents, books, or records to the party's counsel at a specified address, along with an affidavit complying with Section 1561 of the Evidence Code.

The party who issued the deposition subpoena shall mail a copy of the response to any other party who tenders the reasonable cost of copying it.

(d) Physical and mental examinations under Chapter 15 (commencing with Section 2032.010) of Title 4 of Part 4.

(e) The identity of expert witnesses under Chapter 18 (commencing with Section 2034.010) of Title 4 of Part 4.