To stabilize and protect the established diverse character of older, predominately residential neighborhoods, where a mix of housing types and other uses exists. These areas along the fringes of the central business district are characterized by houses generally constructed prior to 1940 and the continued use of these structures as single-family residences is encouraged. The zone is intended to preserve the overall low density residential character of these neighborhoods while also providing for the continuance of certain existing uses that were legally in existence at the time the zone was created. This zone does not permit the construction of new multiple-family dwellings nor their expansion, enlargement or conversion. Commercial uses other than those listed in the commercial land use table (Article 13) are not permitted except in area where the transition overlay zone has been applied. The zone is intended to be applied to those areas designated medium low density residential in the general plan with a minimum district size of one block face or the equivalent. (Amended during the March 2009 supplement.)