Thanks anyway, John.
This was raised with me from a friend who has since contacted Honeywell with the query. Their response was that this was an engineering reference which shouldn't have been incorporated in the handbook - (didn't say what it was, though!).
I did what I should have done first, and trawled through the 'stickies'. There is one reference there in abbreviations and acronyms to VG as Ground Velocity so maybe my guess in the thread opening wasn't far out. Would still like the definitive version, if anyone has it.