Showing a "history" in a pop-up or value list
I've created a kiosk feature for my database that walks a low-level user through data-entry. I'd like to add a field for a purchase order number, but to save time and typing (which increases the chance of error) I'd like the field to be a pop-up that shows the last 2 or 3 values entered as choices. If the user doesn't like the choices they can then enter a new number, but if they are entering 20 items all from the same PO they can just select the first choice quickly. I'm not sure if this is really possible the way I envision it...
I already started experimenting with different formats, but to no avail. All of my other fields in this kiosk area are globals, because I take what is entered and put it in the tables and fields that I want it, and then the process starts over without creating more temporary records. It would be nice if this field was a global too. I've tried using multiple repetitions, but nothing global can be defined in a value list, which is used to pre-populate a pop-up field.
It would be nice if you could use global variables, such as $$PO, to define a value list, but I haven't found that to be possible either. If you get away from using a value list altogether then I believe that means you can't have a pop-up field or a drop-down field...it'll have to be a text field.
What choices or options am I overlooking that could help me out here? Thanks for your input.