Wings on the field

[Forksref]

I'd like some feedback from other crews, regions, states, etc. about your wings. How far onto the field do your wings stand at the snap? We always have been told that we stand with our toes on the OB line and officiate from there unless it is 4th and inches or goal line situation where we move in. I've noticed in some films that the wings are on the field at the snap.