California Code, Elections Code - ELEC § 13206

(a)(1) On the partisan ballot used in a direct primary election, immediately before or above the contest for President, the following words shall be printed on ballots of parties that require registration as a member of the party to vote in the party's primary election:

(2) In the same location, the following words shall be printed on ballots of parties that permit voters who have not disclosed a party preference to vote in the party's primary:

“Party-Nominated Offices

Voters registered as a member of the [name of party] may vote in this primary election for President and party committee.  Some parties may allow voters with no party preference to vote in the party's primary election for President.”

(3) For voting systems that do not allow variance in instructions, the following words shall be printed:

“Party-Nominated Offices

Voters registered as a member of the same party as the candidates may vote in this primary election for President and party committee.  Some parties may allow voters with no party preference to vote in the party's primary election for President.”