(9)   Permitted Areas.
Outdoor advertising signs and non-accessory signs shall be permitted:
(a)   Within the I-2, Medium Industrial district, except within the area bounded by the Delaware Expressway, the Schuylkill Expressway, and Darien Street (extended);
(b)   Within the I-3, Heavy Industrial district; and
(c)   Within the I-P, Port Industrial district.