features, or as set forth in the rules approved by the Director of Planning. Precise boundaries are required at the time of application for, or initiation of, an individual overlay. (Amended by Ord. No. 187,712, Eff. 1/23/23, Oper. 1/22/24; Ord. No. 187,930, Eff. 7/7/23.) C. Development Regulations. The Department of Building and Safety shall not issue a Building permit for a residential Structure within an “HS” Hillside Standards Overlay District unless the residential Structure conforms to the regulations set forth in a specific “HS” Hillside Standards Overlay District. The development regulations for each “HS” Hillside Standards Overlay District shall be limited to changes in the numerical values of the Residential Floor Area, height, and Grading limits in the R1, RS, RE, and RA zones stated in this Chapter (Subdivision 10. of Subsection C. of Section 12.21 - Paragraphs (a) Residential Floor Area, (d) Height Limits, and (f) Grading) and shall not result in a substantial deviation in approach, method of calculation, or measurement from the corresponding language already in place in this Chapter 1. The development regulations shall be determined at the time the overlay is established. The development regulations shall serve to enhance the existing or envisioned character of the overlay.