The voters shall have power to approve or reject at the polls any ordinance passed by the Council or submitted by the Council to a vote of the voters, such power being known as the referendum, except in cases of bond ordinances and ordinances making the annual tax levy. Ordinances submitted to the Council by initiative petition and passed by the Council without change shall be subject to the referendum in the same manner as other ordinances. Within twenty (20) days after the enactment by the Council of any ordinance which is subject to a referendum, a petition signed by currently qualified voters of the city equal in number to at least ten (10) percent of the total number of the qualified voters registered to vote at the last preceding regular municipal election may be filed with the City Secretary requesting that any such ordinance be submitted to a vote of the voters. To be valid, a petition be submitted for the purpose of complying with a referendum election process shall comply with the V.T.C.A., Election Code, as amended and shall be for a subject for which the referendum election process is authorized by state law.