Cal. Gov. Code § 7530
All public agencies, public entities, districts, cities, counties, and cities and counties shall, when being identified by such entity for any purpose, be identified as a public agency, public entity, district, city, county, or city and county, whichever is appropriate.
The requirements of this section shall be deemed satisfied if the words "state," "public agency," "public entity," "district," "city," "county," or "city and county," whichever is appropriate, appears on all letterhead stationery of such public agency, public entity, district, city, county, or city and county, and on all identification cards used to identify a representative of a public agency, public entity, district, city, county, or city and county; provided, that this chapter is not intended to require the reprinting of letterhead stationery or identification cards and any public agency, public entity, district, city, county, or city and county shall have one year from the effective date of this chapter to use up old letterhead stationery and identification cards. The use by a school district of the name "____ City Schools" shall satisfy the requirements of this section.
Notwithstanding any other provision of law, a written application for leave to present a claim pursuant to Section 911.4 shall be granted when it can be shown that the claimant acted with reasonable diligence in pursuing the claim and reasonably believed that the responsible entity was not a public agency by reason of its representations.
Ca. Gov. Code § 7530