What is the test for interpreting a voter-approved statute?

"When we interpret a statute, we attempt to determine legislative intent so as to effectuate the purpose of the law. [Citation.] The first thing we do is read the statute, and do so in an ordinary way unless special definitions are provided. [Citation.] If the meaning of the words is clear, then the language controls. [Citation.] But if the meaning of the words is not clear courts can use interpretative aids; with respect to voter-approved enactments, these aids include the ballot analysis, the official summary, and the arguments presented to the voters.' [Citations.]" (Professional Engineers v. Wilson (1998) 61 Cal.App.4th 1013, 1019-1020, 72 Cal.Rptr.2d 111.)