This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol6", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
All doors must open in the direction in which people pass on leaving the theatre, - that is to say, they must open outwards; and in order that they shall not in any way form an obstruction, they should open right back as far as the wall behind them.
There is another and most important necessity in reference to all doors in connection with exits, and one which needs strict attention, for it must largely depend upon the management of the theatre, namely, all such doors must never be locked or bolted at any time while an audience is in the theatre, except by means of automatic bolts which may be withdrawn by simple pressure against a bar on the inside of the door.
Lastly, in order that the audience may be acquainted with the routes to be taken, and in order to ensure the readiness of all exit doors to be opened, the audience on conclusion of the performance must be permitted to leave the theatre by every exit, while there should be no such thing as an " Emergency Exit."