Mark Mccasland and I came up with an idea for a textbox that will allow users to enter numeric expressions (17+23 will be replaced with 40)

Mark suggested, and I agree that to make it work nicely, we'll have to manually bind the textbox to a field.

I would like to still use the controlsource property to name the field that the textbox is bound to, but I want to handle the updates to and from that field on my own. Where all do I need to place a "nodefault" setting to keep the controlsource from overridding my textbox?

Keep in mind, I have to make sure the textbox is always a character value, and I have to make sure its big enough for the user to enter a reasonable length expression.

Thanks!