Cal. Elec. Code § 14294

At all elections, a member of the precinct board shall mark, on one of the copies of the index posted at or near the polling place, the name of each person who has voted, by drawing a line through the name of the voter, with a pen or indelible pencil. The board member shall mark off the names at least once each hour, to and including 6 p.m. In all counties not using the index roster, the board member shall draw a line under the last name signed in the roster at 6 p.m. or at the time of discontinuation of this procedure, whichever occurs last.