California Code, Health and Safety Code - HSC § 108180

The term “extremely flammable” shall apply to any substance that has a flashpoint at or below 20 degrees Fahrenheit, as determined by the Tagliabue open-cup tester, the term “flammable” or “combustible” shall apply to any substance that has a flashpoint of above 20 degrees to and including 80 degrees Fahrenheit, as determined by the Tagliabue open-cup tester, and the term “combustible” shall apply to any substance that has a flashpoint above 80 degrees Fahrenheit to and including 150 degrees, as determined by the Tagliabue open-cup tester; except that the flammability or combustibility of solids and of the contents of self-pressurized containers shall be determined by methods found by the department to be generally applicable to the materials or containers, respectively, and established by regulations issued by it, which regulations shall also define the terms “flammable” and “combustible” and “extremely flammable” in accord with those methods.