With todays genetic testing it looks like any white markings (not appy or scars or roaning) on a horse are related to one or the other of the pinto patterns.
As far as the socks I have a mare I think I've shown on here before with little socks. She is homozygous for tobiano. No other white on her. She is on my web site. Reflections Paradigm. At the time the UK was developing the DNA test for tobiano this mare, her sire and dam were part of the study. The comment was that they had no idea that a horse so minimally marked would be tobiano. This mare's sire and dam were both blood tested homozygous for tobiano and the U of K thought that one of those tests would be proven incorrect. They DNA tested sire and dam and they proved to both be homozygous for tobi.
Paradigm's white markings on her feet are a sock, a partial sock, a heel and one solid foot. You have to look really close to see some of the white on her feet.
So I would definitely think that pretty boy will test positive for tobiano. And I love his ermin spots! I have a chestnut pinto yearling filly who has them solid around all 4 feet so her feet are chestnut colored instead of white.