It is for touching up some rivets.
I'm sure there are quite a few. Deft 44W007 is an example of white primer with titanium dioxide. If it's just for a few rivets, it may be worth asking for a sample. On the other hand, I needed to do the same kind of touch-up during this year's annual, and the engineer handed me an Alodyne Touch-N-Prep marker and a spray can of Halfords automotive paint, assuring me it would work just fine.