I am talking about the door between AC 2 Tier and AC 3 Tier coaches through which one can move from from one AC 2 Tier coach to AC 3 Tier coach. I have seen that attendants close the doors between sleeper coaches and AC coaches at night. I am asking because four of us are travelling in Kalka Mail. While two of us have been given berths in A1 coach the other two have been given berths in A3 coach. In between these two coaches are B2, B3 and A2 coaches. So we need to move between these coaches to keep contact with each other.