FIG. 18 is a flow diagram of the final zip list function indicated at 616 in FIG. 12 a; FIGS. 19 a and 19 b are a flow diagram of the line index file function indicated at 618 in FIG. 12 a; FIG. 20 is a flow diagram of the zip+4 site polygon check function indicated at 620 in FIG. 12 a; FIG. 21 is a flow diagram of the point in polygon test function indicated at 930 in FIG. 20;