the auxiliary latch means for determining the operative position of the lock bar means in relation to the position of the dead lock means relative to the latch bolt application_number US 42783482 A description in the drawings fig1 illustrates fragmentary portions of a door 10 and its frame 11 with the door in closed position such that the door face plate 12 is opposite the strike plate 13 on the face of the frame the latch mechanism assembly is operably carried in a suitable slim box 14 which is received in the mortise recess 15 substantially as understood in the art the latch mechanism assembly includes a latch bolt 16 movable in response to mechanism not shown operating in the usual way through a link 17 attached to the latch bolt 16 the box 14 is provided with a mounting plate 18 which is covered by the face plate 12 and both plates 12 and 18 are formed with openings to allow the latch bolt 16 to extend into the frame 11 when needed further the latch mechanism includes an auxiliary latch 19 of the type disclosed in peterson u s pat no 3 890 608 and incorporated herein by reference the auxiliary latch has an action such that it affects the operation of link.