A processing system, for use with a user interface display including image elements for prompting user data entry, includes a binding database. The binding database includes elements for linking different first and second data item identifiers with corresponding different first and second prompt elements of a user interface display image. The first data item identifier identifies a set of allowable data items for entry by a user via the first prompt element. A database parser automatically examines the binding database to detect a change in binding database elements. A processor updates the set of allowable data items in response to any detected binding database change.