It is an Amadeus field used to store the FF number for earning purposes.
A simple search of this forum for FQTV would have provided the following recent threads on this:
http://www.flyertalk.com/forum/briti...ights-app.html
http://www.flyertalk.com/forum/briti...nded-fqtv.html
http://www.flyertalk.com/forum/briti...-bookings.html
'Simple' searches don't work well on an iPhone. Thanks anyway.