NCAA OFFICIALS

[Adam]

Basic answer (really really really basic).
You have a Trail, Center, and Lead.
Trail is behind the action. Lead is under the baseline on the same side of the court (left or right facing the basket) as the Trail. Center is on the opposite side, free throw line extended.
When the ball is down low, opposite side of the hoop from lead, lead will cross over to that side. Center then backs towards the half-court line and becomes Trail, and Trail moves to FT line extended and becomes new Center.