Commonly Used Terms

Commonly Used Abbv.


Adjustable Hold Open (AHO) A door closer option which can be adjusted to hold a door open at different positions.

Advanced Variable Backcheck Cylinder (AVB) Optional cylinder that starts backcheck at about 45° instead of the normal 75°.

Alternating Current (AC) An electric current that reverses (alternates) its polarity regularly and continually. It is also known as AC current.

Americans with Disabilities Act (ADA) A US federal law dealing with the minimum standards of building accessibility as well as other issues concerning individuals with disabilities.

Ampere (AMP) The unit of measurement for the rate of current flow.

Annunciator A signaling device which can be either audible or visual.

Anodized An electrochemical process that thickens and toughens the protective oxide on aluminum metal.


ANSI American National Standards Institute publishes standards for commercial hardware. A156.4 is the basic door closer standard.

Anti-Friction Bearing Bearing material between the various moving parts of a hinge.

Applied Stop Surface mounted stop attached to a cased opening frame.

Armor Plate A door protection plate extending a sufficient distance up from the bottom of a door so that carts, gurneys, etc. will contact the plate when pushed against the door.  

Armored Strike A strike reinforced in such a way as to strengthen the frame to which it is applied.

Audit trail A running history of events which occur in an access control system.

Autoequalizer™ An LCN specific term for an electric or a pneumatic power operator. System is low-energy & carries a two-year warranty.

Automatic Closing A code term involving the permitted practice of holding a fire door in the open position providing the door closes upon detection. Generally the detection must be from the presence of visible or invisible particles of combustion. Fusible links are not usually considered acceptable because of slower response time. Any listed closer can be used in combination with an electromagnetic holder and a photo electric or ionization type smoke detector. Labeled or listed spring hinges could be used as well as hydraulic door closers. Some special applications of swinging, sliding and rolling fire doors primarily in industrial applications are permitted to be used with fusible links, weights and pulleys.

Automatic Door The combination of door, operator and controls constituting the system.

Automatic Hold Open (AHO) Available on certain series of closers. Preset at the factory for a specific degree of hold open. The degree of hold-open cannot be changed, nor can the closer be made into a non-hold-open closer.

Automatic Operator The power mechanism causing the opening and closing of a door upon receipt of an actuating signal.

Auxiliary Dead Latch A plunger which, when actuated, automatically locks a projected latch bolt against return by end pressure.

Auxiliary Door Stop Hardware designed and installed to limit the swing of a door.

Auxiliary Lock A lock having a latch bolt or a dead bolt operated by a key or a thumbturn or both. This lock is often used in addition to another lock, which may or may not be key operated, but which has a latch bolt operated by knobs or levers.


Backcheck (BC) A hydraulic function, optional on some door closers, which cushions the opening swing of a door and prevents it from slamming into the stop or wall.

Backset (BS) The distance from the edge of the door to the centerline of the cylinder at the centerline of the door thickness.

Barrier Free (BF) Having to do with the absence of restrictions to access by the handicapped.

Battery backup A backup source of power for an access control system.

Blade Stop Narrow frame stop that will not accept a parallel arm shoe.


Blade Stop Spacer Spacer lowers a parallel arm 1/2” so the arm will clear a blade stop.

Bored Dead Latch (Also called tubular or cylindrical dead latch) A lock fitting round bored openings in the face and edge of a door and having a dead latch operated by a key or thumbturn or both.

Bored Dead Lock (Also called cylindrical or tubular) These are locks or latches fitting round bored openings in the face and edge of a door. If they are key operated, the cylinder is contained in the knob and so occasionally one hears them referred to as "key-in-the-knob-locks." This is imprecise as other types of locks also have cylinders contained in the knobs. The round hole in the face of the door is usually 2-1/8” in diameter and the hole in the edge of the door is 7/8” to 1”. When the lock is installed, the face hole contains the lock body and the edge hole contains the latch bolt.

Bull Nose Trim Face and jamb width joined by a radius rather than a 90° break. Requires soffit shoe.

Butt Hinge (see Full Mortise Hinge)

Bypass Cylinder ME cylinder that will not hold-open within a specified range of door swing.


Cam A component fastened to the back of a mortise cylinder plug or mortise cylinder thumbturn. When rotated, it engages the lock mechanism and either locks or unlocks.

Case The housing of a lock.

Cased Opening Frame section without stops.

Center Hung Refers to a floor closer or pivot where the pivot point is located within the dimension of the door, usually at the center-line of the thickness of a door.

Chain Door Guard A connectable device used to limit the extent to which a door can be opened.

Clamp Flange A spring hinge flange which wraps around the edge of the door and is fastened with thru-bolts and nuts.

Clearance Distance from a PA SHOE to the push side of door or distance from the pull side of door to the wall on 90° installations.


Closing Force Energy generated by a closer to close and latch the door.

Cold Weather Fluid (CWF) A door or floor closer option that should be considered in installations where ground temperature is constantly below +15°F. May be used in temperatures as low as -35°F.

Common (C) A terminal on a form-C relay or single pole double throw switch which is used to complete a circuit.

Continuous Duty The duty rating of an electrical device. Continuous duty rated devices are designed to be powered continually.

Corner Bracket Push side frame mounted adapter used to position closer in frame opening.

Current The flow of electrons measured in amperes (amps).

Current Draw The amount of current (amps) consumed by a device in an electrical circuit.

CUSH Shoe Support Support provides fifth screw anchorage of CUSH shoes on frames with narrow push side reveals.


CUSH-N-Stop Arms (CUSH) Extra duty, parallel arm that includes a stop in the CUSH shoe.

Cylinder (CYL) The cylindrical subassembly of a lock containing a cylinder plug with keyway and a cylinder body with tumbler mechanisms.

Cylinder Assembly Main closer component complete with any mounting plates or electronics.

Cylinder Body The portion of a cylinder that surrounds the plug and contains the tumbler mechanism.

Cylinder Guard Material that surrounds the otherwise exposed portion of a cylinder to protect the cylinder from wrenching, cutting, pulling, or prying.

Cylinder Housing The portion of a lock that surrounds and retains the cylinder body. It can be a knob, part of the lock case or other anchoring means.

Cylinder Plug A tubular portion of the cylinder which rotates within the cylinder body when the correct key is inserted into it and turned.


Dead Bolt A lock component having an end which protrudes from or is withdrawn into, the lock front by action of the lock mechanism. When the door is closed and the dead bolt thrown, it extends into a hole provided in the strike thus locking the door. It does not retract with end pressure.

Deadlocking Latch Bolt A spring actuated latch bolt with a beveled end and incorporating a plunger which, when depressed, automatically locks the projected latch bolt against return by end pressure. Also called dead latch.

Deep Reveal Reveal deeper than what an arm will accommodate.

Delayed Action (DA) A function of a door closer which delays the closing of a door to allow for passage by a wheelchair. It typically permits a door to remain ajar (at approximately 70°) for up to 30 seconds.

Delayed Egress A means of egress controlled (delayed) to prevent pilferage. Delayed egress must meet the requirements of NFPA101.

Direct Current (DC) An electric current that travels in only one direction and typically has a negative and positive polarity.

Door Bolt or Fastener A mechanical device operable from one side of the door and used to fasten the door in a closed position.

Door Edging Protective material applied to the edge of a door.

Door Protection Plates Protective material applied to the face of doors.

Door Pull A device applied to the face of a door which when grasped permits the user to pull a door open.

Double Door Header One automatic electromechanical power operator and one manual door within the same header.

Double Acting A door which swings in both directions

Double Cylinder Dead Bolt Any type of auxiliary lock requiring a key to project or retract the dead bolt (lock or unlock) from either side.

Double Egress Arm (DE) Designed for pull side installation on double egress frames. Actual arm varies depending on selected closer.


Double Lever Arm Two-part arm hinged at the elbow that provides superior leverage. Used on hinge side, top jamb and parallel arm mountings, the geometry of the arm provides greater mechanical advantage to the closer.

Double Pole Double Throw (DPDT) A type of switch or relay (form-C) where two circuits are activated simultaneously.

Double Rabbet Frame Frame with a recess or offset formed on both sides of a stop to receive a door.


Drop Plate Designed to mount a closer on top rail or head frame to meet special conditions or mounting surface dimensions that are below minimums.

Dry Contact Terminals on a relay which do not supply power, but function to open or close a circuit.


Electric Strike An optional, electronic latching device that replaces a regular lock strike in a doorframe that allows the door to open from a remote location or by special access equipment.


Electrohydraulic Power Operator Power operator with an electrically controlled opening feature and hydraulic closing feature.


Electromechanical Power Operator Power operator with an electrically controlled opening feature and closing feature.


Escutcheon An optional, protective or decorative plate that can be installed with many surface mounted actuators.

Exit Device (Also called panic device, panic hardware, panic bolt and crash bar.) A type of lock having an inside release bar. When depressed, the release bar (called crossbar, push pad, etc.) retracts the latch bolt, thus permitting the door to be opened. Most codes require that the activating portion of the release mechanism extend not less than half way across the door. A dogging device allows the release bar to be locked down so that the latch bolt remains retracted and the door can be used as a "push-pin" door. They may or may not be key operated from the outside. These devices have been investigated for panic and are listed by a nationally recognized independent testing laboratory and are also under in-plant follow-up inspection service. They may not be used on fire doors.

Exit Door A door typically used as a means of egress in an emergency.

Extended Length Spindle (ELS) Closer bodies can be ordered with spindle extensions in 1/2" increments to accommodate installation variations such as thresholds or terrazzo pans.

Extra Duty Arm (EDA) Double lever arm with both main and forearm made of solid forged steel for extra strength.


Face The surface of a door, parallel with the face of the door frame.

Fail Safe (EL) (FS) (NFS) A feature of a security device designed to release, for safety purposes, during a power loss, (also known as fail-unlocked, fail-safe or reverse action). The device requires power to be electrically locked.

Fail Secure (EU) (FSE) Referring to an electrically operated lock which in an unpowered state is locked. (Also known as fail-locked, fail-secure or non-fail safe).

Field Selectable An option which can be configured after manufacture, generally as the product is being installed.

Finish The finished color of a lock or other door hardware.

Finish Plate Decorative plate applied to overhead concealed closer to conceal closer mounting plate and screws.

Fire Door A door constructed to provide a specific degree of fire protection. It is typically rated for a period of time as resistant to penetration by fire.

Fire Exit Hardware These are exit devices which have also been labeled for use on fire doors. Dogging devices are not permitted on fire exit hardware as fire doors must have an active latch. When inspecting exit devices on fire doors, look for both labels, one for panic and one indicating the device is fire exit hardware. The label on the fire door itself should also indicate that it is a fire door suitable for use with fire exit hardware.

Fire Rated (FR) A designation for door hardware indicating that it is for use on openings with fire-rated doors.

Fire Shield 22-gage steel liner mounts in the track mortise of the door’s top rail for 20 minute labeled wood doors.


Flush Ceiling Condition when the ceiling is at the same height as the top of the frame.


Flush Panel Adapter Adapter provides PA shoe mounting surface when door and frame are flush.


Flush Transom Shoe Substituted for standard EDA shoe when door and frame are flush.


Forearm Arm part that connects main arm to the shoe attachments in a double lever arm system.

Form-C A type of switch mechanism which includes three terminals: common, normally open and normally closed.

Full Cover (FC) Cover that encloses cylinder assembly except for shaft/arm attachment.

Full Mortise Hinge A hinge having one leaf mortised into the edge of the door and the other leaf mortised into the rabbet edge of the frame.

Full Surface Hinge A hinge having one leaf attached to the face of a door and the other leaf attached to the face of a door frame.

Fusible Link Arm (FL) Releases hold-open function when exposed to high temperatures.


Gravity Pivot Hinge A pivot hinge arranged so the weight of the door causes it to close from an open position or open from a closed position. They are not listed for use on fire doors.

Ground (G) A conducting connection between an electric circuit and the earth.

Guide Rail A separator used to control and separate traffic.


Half Mortise Hinge A hinge having one leaf mortised into the edge of a door and the other leaf attached to the face of a door frame.

Half Surface Hinge A hinge having one leaf attached to the face of a door and the other leaf mortised into the rabbet edge of a door frame.

Hand The orientation of a locking device which matches the bevel or direction or swing of a door. Designations for handing are: RH, LH, RHR, and LHR. On pairs of doors, the suffix -A may indicate that a leaf is the active leaf in the pair (i.e.: RHR-A).

Handed Closer or part designed for ONLY right or left swinging doors.

Header The horizontal member of a door frame above the door.

High Energy Operator A type of automated opener used on a door that should take approximately 2 seconds to open to 90°. High energy operators do require safety devices and guide rails. Conforms to ANSI A156.10.


Hinge Side Face of door and frame on which the hinge pivot point is located.


Hinge Side Mount Mounting with the closer cylinder on the hinge side of the door top rail.


Hinge Side Reveal Depth measured from the frame face to the pull side of the door face.

Hold Open (HO) A door closer option which allows a door to be held open.

Hold-Open Arm (H) Double lever arm that provides hold open function that is either adjustable at elbow or shoe.


Hold-Open Clip Located in track to provide hold-open function for single lever arms.


Hold-Open CUSH (HCUSH) Parallel arm that features solid forged steel main arm and forearm with stop in soffit shoe. Uses control handle to select hold-open function.


Hold-Open Long Arm (HLONG) Hold-open arm extended by a long head and tube for deep reveals.


Hold-Open Track (HO) Track with hold-open clip installed.


Hold-Open Track with Bumper (HBUMPER) Track with hold-open clip and bumper assembly installed.

Holding Force The bond strength of an electromagnetic lock.

Hospital Tips When the ends of a hinge barrel are sloped.


Inrush Current The measurement of amperage that an electrical device needs when power is first applied.

Interconnected Lock (Also known by a number of different trade names) A lock having a separate latch and dead bolt mechanically interconnected and installed in round bored openings in the face and edge of a door. It is best known for providing dead bolt security with the life safety feature of simultaneous retraction. When the dead bolt is projected, a single turn of the inside knob retracts both the dead bolt and the latch bolt. This simultaneous retraction function is also available with some functions of mortise locks.

Intermittent Duty The duty rating of an electrical device which is not designed to be continuously powered.


Jamb The vertical member that forms the sides of a door frame. There is a hinge side jamb and a strike side jamb.


Kick Plate A door protection plate providing protection against the lower portion of the door. 8", 10", 12" and 16" heights are typical. The use of 16" high kick plates is recommended for use on doors used by people in wheel chairs.

Latch Bolt A lock component having a beveled end which projects from the lock front in an extended position, but may be forced back into the lock case by end pressure or drawn back by action of the lock mechanism. When the door is closed, the latch bolt projects into a hole provided in the strike thus holding the door in a closed position.

Latch Speed Separate adjustment to control the last few degrees of the door’s closing swing.

Less All Parts (LAP) A designation for door closers supplied with a closer body only, including no accessories or components.

Lock Front A plate fastened to the edge of a door through which the bolts pass.

Long Arm (LONG) Extended arm for deep reveals or other special applications.

Low Energy Power Operated Door A door that opens automatically upon receipt of an actuating signal, but operates slowly so the kinetic energy generated does not exceed an amount specified.


Maintained Contact Switch A switch designed to continually pass current or close a circuit in its normal condition.

Maximum Opening Furthest degree of door opening.

Maximum Security Pin A hinge pin that cannot be removed when once installed.

Metal Cover (MC) Stamped metal cover required for optional plated finishes and custom powder coat finishes. Standard cover with High Security Series closers.

Momentary Contact Switch A switch designed to pass current or close a circuit on demand.

Monitoring A method of indicating the operational status or security condition of a locking device or a door.

Mop Plate A door protection plate providing protection against floor and rug cleaning equipment. 4" and 6" heights are typical.

Mortise Material removed from frame and/or top rail of door.

Mortise Dead Latch An auxiliary lock fitting a cavity prepared in the edge of the door and having a dead latch operated by a key or thumbturn both. The key or thumbturn engages the lock through holes prepared in the faces of the door.

Mortise Dead Lock An auxiliary lock having a deadbolt instead of a dead latch and otherwise the same as a mortise dead latch.

Mortise Lock A lock fitting a rectangular shaped cavity in the edge of a door. A round hole in the face of the door receives a spindle to which knobs or levers are attached. If key operated, a second round hole above the first receives the cylinder(s) and thumbturn. Some functions use two cylinders which is not a violation of the codes because the inside knob always operates. Some functions use two cylinders which sometimes is a violation of codes because the inside key projects a dead bolt or locks the inside knob which can only be unlocked by key. (This example of key operation on the inside applies equally to other types of locks and is mentioned under mortise locks only because it originated with them.)

Multi-Point Hold-Open (ME) Infinite hold-open points from 0° up to maximum opening.


NFPA 101 National Fire Protection Association life safety code.

Non-Handed Closer or part designed for both right and left hand swinging doors.

Non Hold-Open (NHO) Indicates a door closer that is not equipped with any hold open feature.

Non-Removable Pin A hinge pin secured by a set screw or other means.

Non-Sized Cylinder assembly with spring power adjustable over a range of sizes.

Normally Closed (NC) The normal condition of a switch or relay contact in which a circuit is closed.

Normally Open (NO) The normal condition of a switch or relay contact in which a circuit is open.


Offset Hung Refers to a door closer or pivot where the pivot point of the door is offset from the surface of the door. Typical offset dimensions are 3/4" or 1-1/2".

Olive Knuckle Hinge A pivot hinge with a joint shaped like an olive.

Opening Force Force required to open the door against the closers spring power.

Operating Current The measurement of amperage that an electrical device needs after the device has been initially powered.

Overhead Concealed Closer with cylinder concealed in head frame and either a concealed or exposed arm.


PA Shoe Attaches the forearm to the soffit for a parallel arm system.


PA Shoe Adapter Adapter provides horizontal mounting for PA shoe on a flush door and frame.


Panic Breakaway Stop An optional safety device that permits egress on in-swinging exterior doors by allowing them to swing out in case of an emergency. Used with overhead concealed, center pivoted in-swinging doors.


Parallel Arm A push side mounted double lever arm system where main arm is parallel to the door when in the closed position.


Parallel Arm Holder (PAH) An item usually used on the inactive leaf of a pair of doors for hold-open where the active leaf has a closer installed.

Physically Handicapped Refers to door closers that are preset with 5 pounds of opening force.

Pivot Hinge A hinge with a fixed pin and a single joint having a height less than the adjacent hinge leaves.

Plain Bearing (non-bearing) When no bearing material is between the various moving parts of a binge.

Pneumatic This type of LCN Automatic Operator is driven by an air source. The air source can be built into the control box or provided separately within the building.

Power Assist Door A door furnished with a power mechanism that reduces the opening resistance of a self closing door.

Power Operator A term used to describe a type of automated opening system. Refer to “Automatic Operators”

Pull Bar A device extending across a door which when grasped permits the user to pull a door open.

Pull Plate An assembly consisting of a Door Pull with protective material positioned between Pull and face of door.

Pull Side Hinge side of door.

Push Bar Similar to a Pull Bar but used for pushing a door open.

Push Plate Material applied to the surface of a door and located where a user pushes on a door to open it.

Push Side Face of door on stop side of frame.


Rabbet Recess or offset formed in the face to receive a door.


Radio Frequency (RF) A method of actuating Automatic Operators. A RF transmitter signals a RF receiver to open a door.

Rail One of the horizontal members of a door.

Raised Barrel A full mortise hinge having an offset barrel.

Recessed Cylinder A cylinder where the cylinder head is flush with, or recessed below, the outside surface of the trim to protect the cylinder from wrenching, cutting, pulling or prying.

Rectifier An electrical device which allows current to flow in one direction only. It converts AC current to DC.

Regular Arm A double lever, non hold-open arm.

Regulating Screw Valve that adjusts flow of hydraulic fluid within cylinder to control door closing speed.

Request to Exit (RX) A monitor or switch that signals an authorized request to exit a protected area.

Reveal The distance between the face of a door frame and the face of a door.

Roller Latch A mechanical device used to fasten a door by means of a rolling plunger which engages a socket or catch. These have become somewhat obsolete where self-closing or automatic closing is used due to the resistance a roller latch provides against complete door closing. They are not permitted in health care facilities under some codes.

Rotational Indicator An indicator located on the spring adjuster. Used when adjusting spring power to indicate each revolution.


Safety Guard A product that mounts on the hinge edge of the door. This is a heavy-duty vinyl product that covers the opening between the door and frame where many injuries occur. One suggested use is on doors within childcare facilities.

Safety Stud A projecting member on one surface of a full mortise hinge leaf that engages a hole in the opposite leaf when the door is closed.

Safety Zone The area on the swing side of an automatic door protected with safety mats or sensing devices to prevent the door from operating when the area is occupied by persons or objects.

Sealed Closer (SC) Where water contact may occur with a floor closer. It provides gasketing and a cover plate that are epoxied around the cement case with the floor closer inside. This option is only available for replacement closers when the cement case is also replaced.

Selective Hold Open (SHO) A door closer option which allows a door to be held open and can be enabled or disabled on demand.

Self-Closing Again, code language indicating that whenever opened, a door returns to the closed position. Accomplished with any labeled or listed closing device or spring hinge.

Sensing Device A device that detects the motion or presence of a person or object. Motion sensors or detectors, presence sensors and photo-cell systems are all sensing devices and are used instead of control mats and sometimes in combination.

Sequence An option to the LCN series of automatic operators. This option allows a pair of vestibule doors to open one after the other.


Shoe Attaches forearm to frame or door face in a double lever arm system.

Silent Operation The quiet operational mode of a locking device which typically buzzes or makes other noise when energized.

Simultaneous Pair Two automatic doors that open at the same time.

Single Acting A door which swings in only one direction.

Single Lever (Standard) Arm (STD) Directly connects cylinder and track/roller assembly on the door or frame.


Single Point Hold-Open (SE) Electrically controlled hold-open using a special track and single lever arm.

Single Pole Double Throw The description of a form-C contact.

Single Pole Single Throw (SPDT) A switch with only two terminals which either close or open a circuit.

Sized A closer with a specific closer power for proper door applications.

Slide-In Hinge A hinge where one or both leaves slide into a cavity prepared in a door or door frame, thus concealing one or both hinge leaves.

Slim Line Cover A cover that conceals the cylinder but exposes both pinion shafts.


Soffit Horizontal surface of a frame between vertical stops on a double rabbet frame.

Soffit Shoe Connects parallel arm shoe to soffit.

Spring CUSH Arm (SCUSH) Non-handed parallel arm for abusive applications. Features solid forged steel main arm and forearm with spring loaded stop in the soffit shoe.

Spring Hinge A hinge with flanges or leaves which attach to the door and jamb and are connected to the hinge pivot point(s) (barrel). Springs provide energy to close a door from the open position or, in some cases, open a door from the closed position. Single acting spring hinges are often listed for use on fire doors.

Spring Hold-Open CUSH Arm (SHCUSH) Non-handed parallel arm for abusive applications features solid forged steel main arm and forearm with spring loaded stop in the soffit shoe. Uses control handle to select hold-open function.

Spring Pivot Hinge A spring hinge employing pivot points at the top and bottom edges of a door.

Spring Power Closing force exerted by the spring inside the cylinder to close the door.


Spring Power Adjustment Mechanical pre-loading of spring to adjust closing force.


Standard Cylinder Cylinder with main speed, latch speed, and backcheck adjustments.

Stile The vertical member of a door to which a locking device is installed.

Stop The part of a door frame against which the door closes.

Strike A plate fastened to the door frame or the inactive leaf of a pair of doors into which the bolts project.

Strike Box A housing used in back of a strike to enclose the bolt openings.

Swaging Offsetting a hinge leaf at the barrel so the surface of the leaf is not tangent to the outer diameter of the barrel.

Swing Clear Hinge A hinge that swings a door completely clear of the opening when the door is opened 90° to 95°.

Swing Free Arm ME arm designed to allow free movement of the door without disengaging the holding mechanism.


Tailpiece (TP) A bar projecting from the back of a rim or bored lock cylinder engaging the lock mechanism and when rotated by the key or thumbturn either locks or unlocks.

Thumbturn (TT) The component that projects or retracts a dead bolt or latch bolt by grasping with the thumb and fingers and turning. Sometimes called a turnpiece or turn.

Time Delay A pre-set period of time when a circuit is either open or closed in order to activate a locking device.

Top Jamb Mounting with closer installed on frame face.

Top Rail Horizontal top member of a door that connects the latch and hinge stiles. Height is measured from stop on push side.


Torx Security machine screw with TORX drive and security pin for tamper resistant applications.


Transformer Electrical device to reduce voltage from 120V AC to 24V AC.

Tri-Volt A triple voltage option on some magnetic holders which allows multiple input voltages.


UL listed (UL) A listing in the UL directory for a device which has passed specific Underwriters Laboratories tests.

Universal A term used to describe a door closer. Closers of this nature are non-sized and non-handed.


Vestibule A small lobby or entrance that has at least two doors. One door is to the exterior and the other to the interior of the building. A variation could be multiple doors or banks of doors.

Volt (V) Unit of measurement of electrical current.


AHO - Automatic Hold-Open
AC - Alternating Current
ADA - Americans with Disabilities Act
AF - Armored Front  

AFB - Automatic Flush Bolt

AHJ - Authority Having Jurisdiction
AL - Aluminum  

AMP - Ampere
AMS - All Machine Screws

ANSI - American National Standards Institute

AST - Astragal

AWS - All Wood Screws

BB - Ball Bearing

BC - Backcheck
BHMA - Builders Hardware Manufacturers Association
BF - Barrier Free
BS - Backset  

BTB - Back to Back

C - Common
CD - Cylinder Dogging

CSK - Counter Sunk
CTC - Centerline to Centerline  

CTE - Center to End 

CWF - Cold Weather Fluid
CYL - Cylinder  

DA - Delayed Action
DC - Direct Current
DE - Delayed Egress

DPDT - Double Pole Double Throw
DPS - Door Position Switch

DT - Dummy Trim

EL - Fail safe
ELR - Extra Long Rod

ELS - Extended Length Spindle
ES - Latch Retraction 

ESC - Escutcheon

ETR - Top Rod Extension 

EU - Fail Secure
F - Fire Rated
FL - Fusible link  

FS - Fail Safe
FSE - Fail Secure
G - Ground
GMK - Grand Master Key 

HO - Hold-Open
KA - Keyed Alike 

LAP - Less All Parts
LBR - Less Bottom Rod 

LC - Less Cylinder

LDW - Less Door Width
LH - Left Hand

LHR - Left Hand Reverse  

LM - Latch Monitor

MK - Master Key

MS - Machine Screws 

MS - Monitor Switch

NC - Normally Closed
NFS - Non-Fail Safe
NHO - Non Hold-Open
NL - Night Latch

NO - Normally Open
NRP - Non-Removable Pin  

PA - Parallel Arm  

PAH - Parallel Arm Holder

RF - Radio Frequency

RH - Right Hand

RHR - Right Hand Reverse  

RK - Removal Key

RX - Request to Exit
SB - Sex Bolt

SC - Sealed Closer
SHO - Selective Hold-Open
SNB - Sex Nut and Bolt

SPDT - Single Pole Double Throw
SPST - Single Pole Single Throw
SS - Stainless Steel

TB -Through Bolts

TJ - Top Jamb

TP - Thumb Piece/Turn Piece

TT – Thumbturn

UL – Underwriters Laboratories

V - Volt

VA - Volt-Ampere

VAC - Volt Alternating Current

VDC - Volt Direct Current

WS - Wood Screws 


Arm Options

STD - Standard Arm

REG - Regular Arm

H - Hold Open Arm

LONG - Long Arm

XLONG - Extra Long Arm

HLONG - Hold Open Long Arm

EDA - Extra Duty Arm

HEDA - Hold Open Extra Duty Arm

CUSH - Cush -n- Stop Arm

HCUSH - Hold Open Cush -n- Stop Arm

SCUSH(SCNS) - Spring Cush -n- Stop Arm

SHCUSH(SHCNS)- Spring Hold Open Cush -n- Stop Arm

SF - Swing Free Arm

DE - Double Egress Arm

FL - Fusible Link Arm


Control Box Options

SC - Standard Control Box

PC - Premium Control Box


Cylinder Options

STD - Standard Cylinder

DEL(DA) - Delayed Action Cylinder

AVB - Advanced Variable Backcheck


Cover Options

STD - Standard Plastic Cover

MC - Metal Cover

LL - Lead Lined Cover

FC - Full Cover

CL - Cover Length


Track Options

STD - Standard Track

HO - Hold Open Track


Fastener Pack Options

WMS - Wood & Machine Screws

TBWMS - Thru-Bolt, Wood & Machine Screws

SRT - Self Reaming & Tapping Screws

TBSRT - Thru-Bolt, Self Reaming & Tapping Screws

TORX - ‘Torx’ Machine Screws

TBTRX - Thru-Bolt, ‘Torx’ Machine Screws