Glossary terms - D


Uses a smart card to securely manage the movement of access rights and audit history through a credential-based network.


A bolt having no bevel or spring action; operated by turning a thumbpiece, lever or key.


A lock that has a deadbolt only.

Deadlocking Latchbolt

A plunger type bolt parallel to the latchbolt of a lock that is held in a depressed position when the door is closed and the main latchbolt is retained by the strike on the frame. It prevents the bolt from being forced back toward the lock if pressure is applied during attempted forced entry.Term used primarily in conjunction with cylindrical locks (See also AUXILLARY DEAD LATCH).

Delayed Action

Slows door closing speed between maximum opening and approximately 70º. Often specified to meet barrier-free codes which require delayed closing.


A device that allows current to flow n one direction and not in the other direction.

Direct Current (DC)

Electric current that flows in one direction. Example: battery power.

Disposable Construction Core

Used with removable core keying, where non-essential locking doors are used within a construction project. Locks are supplied with disposable plastic cores.

Dogging Device

(exit device) – A part of the exit device that, when activated, will hold the crossbar or push rail in the fully depressed position at all times,thereby holding the latchbolt of the exit device in retraction. This allows for free operation and access of the door from both sides. Mechanical dogging such as this is usually achieved by means of an allen type screw to activate the hold-down mechanism. Cylinder dogging replaces the allen key (DOGGING KEY) with a keyed hardware cylinder. Labeled doors are only able to be dogged by electrical means and not with a positive mechanical device.

Dogging Key

A key or tool used to dog an exit device.

Door Opening

The opening dimension of a doorway, measured between jamb rabbets and from the floor to the frame header rabbet. CLEAR OPENING is measured after deducting for frame stop projections and any portion of the door(s), when open, left protruding into the opening.

Door Position Switch (DPS)

A switch used to monitor whether a door is in an open or closed position.

Door Protection Plates

Protective material applied to the face of the door and generally made of brass, bronze, aluminum, stainless steel or laminated plastic.

Door Stop

A device to stop the swing of a door.

Double Acting Door

A door that swings in either direction. Prepared for pivots or spring hinges that allow the door to swing approximately 90 degrees. Hung from a Cased Opening Frame.

Double Egress Frame

A special profile frame prepared to mount two (2) single acting doors swinging in opposite directions (both doors have the same hand). If a labeled opening both doors must have a fire rated vertical rod device. Operable trim is never necessary on the ingress side of either door.

Double Lever Arm

A two part arm connected at the elbow that is part of a door closer providing superior leverage and the geometry provides greater mechanical strength.

Double-throw Bolt

A lock bolt that can be projected (thrown) beyond its initial position into a fully extended one.

Drill Resistance

Arranging a cylinder plug and housing to resist drilling.

Driver Pins

The upper set of keying pins in a pin tumbler cylinder. The drivers are under constant spring tension toward the cylinder plug and are pushed upwards when raised by the insertion of a key into the cylinder.

Drop Escutcheon

A lock escutcheon that has a pivoted plate that “drops down” and covers the keyhole.

Dummy Cylinder

A decorative hardware trim that simulates an actual cylinder but has no operable parts.

Dummy Trim

Lock trim only without the lock; used primarily on the inactive leaf of a pair of doors or on a door for a pull type function where no locking or latching is required. Trim may be specified as ½ dummy trim for one side only mounting or full dummy trim to mount on both sides of the door leaf.

Dust Proof Strike

A floor mounted strike sometimes used with flush bolts and exit devices, which has a spring-loaded plunger or cap that fills the strike hole when the bolt or latch is not engaged.

Dutch Door

A door divided horizontally so that the lower part can be shut while the upper part remains open.