Nadya:

You can set up your combo box to have multiple columns and only show the field name column. The other columns could store information like ControlSource, DataType, Len, Dec, Format, InputMask, etc... Use the information stored in the other columns to change the textbox properties in the InteractiveChange event.

As an alternative, just use two columns (field prompt, field name) and fetch the field properties (and change the textbox properties) in the InteractiveChange event.

My gut feeling tells me this is low to medium difficulty and easy to maintain.

Hope it helps,
Daniel