I should add: I started down this road because an FVD db text file I exported a year ago refused to later import. It turns out there were gaps in the 'groups' details FVD had exported; when I added a dummy entry for these missing Group numbers, viola! - successful import! (I'm not sure why FVD doesn't clean this up when Groups are removed within the program).

Makes it FAR easier to debug exports with errors (which won't re-import).