BOAC- OK that makes sense, but i guess I'm thinking of the following situation-
Tower ask you on lining up to "maintain 3000'on reaching". The SID requires 3000' as well and we check into the sector saying "Callsign passing 1700' BPK 1A cleared 3000". Same call in both cases but very different clearances. It could be quite easy for ATC to think we know we are held down when WE don't....maybe we didn't get the message from tower or even worse maybe we have forgotten!!(helped along by making the same call in both cases)