Add to ORKGSenate Constitutional Amendment No.6. Amends Sections 4 and 6 of Article XXIV of Constitution. Exempts from state civil service officers and employees of district agricultural associations employed less than six months in calendar year; stewards and veterinarians of California Horse Racing Board employed on part-time basis. Prohibits Legislature from reviving any optional exemption from state civil service after once abolishing such exemption. Permits given position to be filled by successive temporary appointees, unless employment list is in existence; increases maximum employment period of temporary appointees to nine months in any consecutive 12-month period