It does say "a coach" but under definition of coach it says anyone who occupies a coaches box or assists in the direction of the team. Their are 2 coaches boxes on the field and any number of people in the dugout could theoretically be assisting in the direction of the team.
That being said, I have had UIC's tell me both ways on this. Some only want you to communicate with the head coach, others dont care as long as it is a coach of the team. I can see the argument for only speaking with a single reprentative from each team as this keeps any translation of the conversation from clouding what was actually discussed and both the umpire and coach have full knowledge of any other discussions during the game.



























