California Harbors and Navigation Code
Sec. § 18


Signature or subscription includes mark when the signer or subscriber can not write, such signers or subscribers name being written near the mark by a witness who writes his own name near the signers or subscribers 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.
Source
Last accessed
Jun. 6, 2016