The article above written by Sarah V Schweig has a few mistakes.
1. Not a birthmark 2. Not a chestnut 3. The white marking is not on his flank, it is over his shoulder (flank is a little further back past his barrel.)
4. The white marking makes him a paint - a tobiano paint All in all the white marking is neat and it looks like he has two hearts on his neck and Vinnie is very handsome.