Propositions are legislation; specifically, they are one of:
(1) initiatives which are exercises of legislative power reserved by the people to adopt a law initiated by citizen petition,
(2) referenda which are exercises of legislative power reserved by the people to approve or reject measures passed by the legislature, either with the assent of or over the veto of the governor.
(3) legislation referred to the people by the legislature (often because it would impact a previously passed initiative statute in a manner which the legislature has not been delegated the power to do without popular assent.)
Prop 13 of 1978 (proposition numbers get reused, so “Prop 13” alone is technically, though only rarely practically, ambiguous—though confusion from that ambiguity has been suggested to have helped the defeat of Prop 13/2020, which was on the ballot with two measures that would have modified Prop 13/1978, Prop 15/2020 [which failed] and Prop 19/2020 [which passed]), specifically is an initiative constitutional amendment.
(1) initiatives which are exercises of legislative power reserved by the people to adopt a law initiated by citizen petition,
(2) referenda which are exercises of legislative power reserved by the people to approve or reject measures passed by the legislature, either with the assent of or over the veto of the governor.
(3) legislation referred to the people by the legislature (often because it would impact a previously passed initiative statute in a manner which the legislature has not been delegated the power to do without popular assent.)
Prop 13 of 1978 (proposition numbers get reused, so “Prop 13” alone is technically, though only rarely practically, ambiguous—though confusion from that ambiguity has been suggested to have helped the defeat of Prop 13/2020, which was on the ballot with two measures that would have modified Prop 13/1978, Prop 15/2020 [which failed] and Prop 19/2020 [which passed]), specifically is an initiative constitutional amendment.