For those not familiar with the veto what can it be used for?
As it suggests, in theory any new rules if the right justification was made. In practice, and this is generally Ferrari's defence, rarely used. If you are a subscriber, here is Dieter Rencken looking at the veto in historical context.
This writer put the history of said veto, previously never publicly discussed, to current FIA president Jean Todt (Mosley disbanded FISA in 1993, with motorsport now a fully-fledged pillar of world motoring's governing body). Saliently Todt was Ferrari team boss from 1993 to 2006, and CEO thereafter, so is perfectly placed to comment.
"At the time I joined Ferrari in  I tried to understand what was the story behind it, and the story was simple," he explained.
"Enzo Ferrari, the founder, said he felt very isolated in Maranello to all the British teams, so he needed a protection, because he was alone. You'll remember the time we are talking, it was , Ferrari was the only full car manufacturer, engine, chassis. [ED: Renault and Alfa Romeo were also full 'works' teams at this point]
"And he was fighting private teams like Williams, Lotus, McLaren, which were all using the same engine, which if I remember was the Ford Cosworth. So he got that in his discussion, by implementing [the veto]."
Most recent use (I think) was in 2015: