Using Drop Down List Content Control

When I am in design mode and am adding options to a Drop Down List Content control field, I get two texts to fill in; "Display Name" and "Value"
My thoughts were that I could enter two separate texts, i.e something simple for "Display name" and more complex for "Value" but it seems that whichever field I fill in, the other mirrors it exactly. Is there a trick to this?

By default, Word fills both with the same value. You can delete/edit/overtype either one.

Okay, that was easy. It still doesn't give me what I want though.
I want a dropdown of nominal dimensions (which the user would know) but I want it to show real dimensions (which the user may not know)
For example, a 2x4 piece of lumber is actually 1.5 x 3.5.
I want them to see "2x4" in the dropdown but when chosen, "1.5x3.5" will appear in the field. Is that possible?

See, for example: http://www.msofficeforums.com/word/1...own-lists.html

Thank you! I think that is exactly what I need. It gives me something to play around with, at any rate. Color this thread solved.