Sec. 4. As used in this chapter, "downtown" refers to:
(1) the central business district of a city, town, or township;
(2) any commercial or mixed use area within a neighborhood of a city, town, or township that has traditionally served, since the founding of the community, as the retail service and communal focal point within the community;
(3) an enterprise zone established under IC 5-28-15; or
(4) a brownfield revitalization zone established under IC 6-1.1-42.