(4) Designated blighted area For purposes of this subsection— (A) In general The term “designated blighted area” means any blighted area designated by the governing body of a local general purpose governmental unit in the jurisdiction of which such area is located. (B) Blighted area The term “blighted area” means any area which the governing body described in subparagraph (A) determines to be a blighted area on the basis of the substantial presence of factors such as excessive vacant land on which structures were previously located, abandoned or vacant buildings, substandard structures, vacancies, and delinquencies in payment of real property taxes. (C) Designated areas may not exceed 20 percent of total assessed value of real property in government’s jurisdiction (i) In general An area may be designated by a governmental unit as a blighted area only if the designation percentage with respect to such area, when added to the designation percentages of all other designated blighted areas within the jurisdiction of such governmental unit, does not exceed 20 percent. (ii) Designation percentage For purposes of this subparagraph, the term “designation percentage” means, with respect to any area, the percentage (determined at the time such area is designated) which the assessed value of real property located in such area is of the total assessed value of all real property located within the jurisdiction of the governmental unit which designated such area. (iii) Exception where bonds not outstanding The designation percentage of a previously designated blighted area shall not be taken into account under clause (i) if no qualified redevelopment bond (or similar bond) is or will be outstanding with respect to such area. (D) Minimum designated area (i) In general Except as provided in clause (ii), an area shall not be treated as a designated blighted area for purposes of this subsection unless such area is contiguous and compact and its area equals or exceeds 100 acres. (ii) 10-acre minimum in certain cases Clause (i) shall be applied by substituting “10 acres” for “100 acres” if not more than 25 percent of the financed area is to be provided (pursuant to the issue and all other such issues) to 1 person. For purposes of the preceding sentence, all related persons (as defined in subsection (a)(3)) shall be treated as 1 person. For purposes of this clause, an area provided to a developer on a short-term interim basis shall not be treated as provided to such developer.