SIGNATURE or SUBSCRIPTION includes a mark when the signer or subscriber cannot write, such signer's or subscriber's name being written near the mark by a witness who writes his own name near the signer's or subscriber's name; but a signature or subscription by mark can be acknowledged or can serve as a signature or subscription to a sworn statement only when two witnesses so sign their own names thereto.
('86 Code, § 1.04.270)
Statutory reference:
For statutory definition of signature or subscription, see Cal. Gov't Code § 16