Not my specialist subject either, but my understanding is that it relates to the furthest distance a twin-engined aircraft is allowed to fly away from a field capable of taking it in case things go quiet. To be allowed to do the trick, the airline has to demonstrate the reliability of the aircraft and its engines in their operation - for a year. I would imagine, thinking about it, that VS would use a twin on DXB, the Indian routes, possibly Lagos, but I can't see it on the Atlantic in VS colours any time soon.