Overlay districts are areas in Firebaugh that may require special regulations due to unique locational features, architecture, historical significance, resources or hazards. These districts may be combined with any of the base districts identified in this Chapter. For purposes of identification on the Official Zoning Map for Firebaugh, districts that are joined with an overlay district shall be suffixed with the name of the overlay district. As an example, the zoning for an area of Firebaugh that is classified central commercial (C-2) and contains the historic downtown, which demands unique design regulations, would read as C-2 (PD), Central Commercial, Planned Development District. Firebaugh overlay districts are as follows: