Initiative and referendum petitions authorized to be filed under provisions of this title, or authorized by charter, or authorized for code cities having the commission form of government as provided by chapter 35.17 RCW, shall be in substantial compliance with the provisions of RCW 35A.01.040 as to form and content of the petition, insofar as such provisions are applicable; shall contain a true copy of a resolution or ordinance sought to be referred to the voters; and must contain valid signatures of registered voters of the code city in the number required by the applicable provision of this title. Except when otherwise provided by statute, referendum petitions must be filed with the clerk of the legislative body of the code city within ninety days after the passage of the resolution or ordinance sought to be referred to the voters, or within such lesser number of days as may be authorized by statute or charter in order to precede the effective date of an ordinance: PROVIDED, That nothing herein shall be construed to abrogate or affect an exemption from initiative and/or referendum provided by a code city charter. The clerk shall transmit the petition to the county auditor who shall determine the sufficiency of the petition under the rules set forth in RCW 35A.01.040. When a referendum petition is filed with the clerk, the legislative action sought to be referred to the voters shall be suspended from taking effect. Such suspension shall terminate when: (1) There is a final determination of insufficiency or untimeliness of the referendum petition; or (2) the legislative action so referred is approved by the voters at a referendum election.