Data Element Mapping

Allow field mapping at the DATA ELEMENT such that every source mapping can see that a mapping exists. Very useful for DEFAULT or NOT USED fields, or derived fields that were dependant on other values.

Supporting this will help to streamline mapping sessions where too much time can be spent discussion fields that already have a known mapping.

It should be possible to flag a Mapping as being a fixed mapping, or allowing a Source Mapping to override that mapping if needed.