Lookup Button <F6>
This button activates a browse box. It is always placed directly to the right of an entry field and allows you to select a value for the entry field from the browse box. The browse box usually has all the same functions as if you had selected it from the main menu, so you can add, edit or delete records in the browse without leaving your original task.
Pressing <F6> on your keyboard when you are in a field with a lookup button works the same as pressing the Field Lookup button itself!