OK, there is something I've heard announcers and others refer to numerous times, but for the life of me, I can't figure out what they are talking about. When a referee is spotting a ball, I've heard people comment about whether they are using their left foot or right foot for the spot. I heard it again on tonight's Texans broadcast. It seems to have some influence on where the ball is placed (but why?), and thus how likely it is that a player makes a 1st down in a close situation. Does the referee "choose" which foot to use, and if so, how much difference does this make? Can someone give me some insight, here?