The Historic Landmark “L” Combining District shall be utilized to denote those properties which have been designated by the Board of Supervisors as Historic Resources pursuant to the provisions of the County Code, Chapter 16.42, Historic Resources Preservation. (Ord. 2493, 10/18/77; 3344, 11/23/82; 3432, 8/23/83; 3927, 6/28/88)