It may be useful to cycle through the columns that are on a datawindow. You can do this by accessing the columns by number.

long ll_column_count
string ls_col_name, ls_col_tag, ls_col_type

ll_column_count = Long(Describe("Datawindow.Column.Count"))
FOR ll_index=1 TO ll_column_count
   ls_col_name = Describe("#" + String(ll_index) + ".Name")
   ls_col_tag = Describe("#" + String(ll_index) + ".Tag")
   ls_col_type = String(Describe("#" + String(ll_index) + ".ColType"))
NEXT