It simply overwrites all the existing fields of text with the vlookup reference. Example:
Before:
Disposition
Disposition
Disposition
Disposition
Disposition
After:
#REF (=VLOOKUP(F5,'[Center List.xls]Sheet1'!A$2:B$350,2,FALSE)
#REF (=VLOOKUP(F6,'[Center List.xls]Sheet1'!A$2:B$350,2,FALSE)...