The city council may adopt guidelines to implement and interpret measure N and measure R, following public notice and public hearing; provided, that any such guidelines shall be consistent with measure N. Any such guidelines must be adopted by four- fifths (4/5) affirmative vote of the total authorized membership of the city council. (§ 4 of measure N, passed by voters 11-3-1987: § 16 of proposition R, passed by voters 11-7-1978)