an ordinance, followed by actions of this commission, and additional proposals from supervisor winer anener and kim. when this commission heard that ordinance, it recognized both -- to encourage the production of student housing and protection of the existing housing stock. satisfying this requirement is expensive at over $53,000 per unit. the next step, land-use controls. the ordinance provided exemption, a recognize the difference between student housing and other residential uses, but it did not establish a system of land use controls. the condition -- the commission asked staff to follow up. you decided worst in housing should be permitted, established a definition -- you decided where student housing should be permitted, and established a definition. it should not be converted from existing units. your action applied to all housing types, from single- family, apartment buildings. sros were not singled out at that time. the supervisors amendments, we are here today to discuss the prohibition on conversion of existing housing. conversion of existing housing, since housing would be permit