Masking with views is a interesting approach to combine with defaults though unwieldy I guess, you need an 'insert' view and an everything else view. Colin, I'm kinda with you, except in practice not everyone has a data dictionary (or reads it). It is perhaps an interesting thing to scan for before applying a change, looking to see if they are overriding a default.

I appreciate the comments, wasn't sure how this topic would be received!