Where is the subsequent throw in from.

[rbruno]

Player A-1 is out of bounds along the endline for a throw in. He throws the ball which is caught by B-1 with his foot on a sideline boundry line. Where is the subsequent throw in... on the endline or the sideline where the throw in was caught. Is this the same as throwing the ball directly out of bounds without being touched because the ball never touched in bounds/