Act Curtain - A curtain (sometimes designed for a specific show) that is opened to signal the beginning of a performance. The front curtain is often used for this purpose.

Acting Area - The stage area used by actors for performances.

AIA - American Institute of Architects

ANSI - American National Standards Institute

ANSI Z 359.1  - American National Standard Safety Requirements for Personal Fall Arrest Systems, Subsystems and Components. 

Apron - The portion of stage that extends beyond the proscenium opening.

Apron (Forestage) - The area of the stage located just in front of the proscenium.

Arbor - A carriage or rack that contains weights, usually flame cut steel or cast iron, in sufficient quantity to balance a load.

Arbor Pit - An area located below an opening in the stage floor that permits greater travel for counterweight arbors and pipe battens.

Arbor Release - A part of the fire curtain rigging that permits the fire safety curtain arbor to move and the fire curtain to close. The release is usually controlled by the fire line system.

Arena - A performance space with seating all around the performers.  Examples include theaters, basketball courts, and indoor rodeos.

ASA - Acoustical Society of America

As Built Drawings - Equipment or layout drawings that show equipment as it was actually built and intended to be installed. They may not reflect actual, as installed, conditions.

ASME - American Society of Mechanical Engineers

ASTC - American Society of Theater Consultants

ASTM - American Society for Testing of Materials

Audience - The area of the theater where visitors sit to view a stage performance

Auditorium - A hall or seating area within the hall where the audience views a performance

Austrian Curtain - A curtain that is raised (opened) with brailed lifting lines and is sewn with both vertical and horizontal fullness.

AWG - American Wire Gauge - used to identify wire diameters.

Backstage - The stage area that is located beyond the sight of the audience. Usually behind curtains and other masking devices.

Balcony - A raised platform extending out from a wall, often used for additional rows of seats in an auditorium.

Banner Hoist - A hoist with a smooth drum designed to roll up a cloth banner. Usually used with curtains intended to modify the acoustic properties of a space.

Bar Joist - A beam fabricated using lightweight rolled or fabricated sections that is used for long spans under light loading conditions.

Batten - A bar, usually made from steel pipe, from which scenery, lights, and curtains are hung.

Batten Clamp - See "Pipe Clamp"

Beam - A structural member (usually horizontal in a building structure) that resists bending.

Beam Clamp - A device from which a load is hung, attached to the flange of a steel beam without altering the beam in any way.

Belaying Pin - A wood or steel rod, inserted into a hole in a pin rail, that secures ropes attached to a load. They are typically removable.

Bi-Parting Drape - A curtain that opens from the center to either side.

Black Box - A room (often painted black) that is intended for performance and lacks a permanent configuration, seating, or fixed performance area. 

Block - An assembly that consists of one or more sheaves and axles in a housing.

Boom - A vertically mounted pipe used for stage lights.

Border Curtain - A curtain used to define the top limit of the stage and to mask or hide lights and unused scenery and curtains.

Box Boom - Originally a vertical pipe in a seating box used for stage lights, but now used to indicate any side lighting position.

Brail Curtain - A curtain that is raised (opened) with brail type lift lines and is sewn flat or has horizontal fullness.

Brail Lines - Lifting lines that pass through a row of rings sewn to the back of the curtain and attach at the curtain bottom. The curtain folds up when the lines are pulled.

Breaking Strength - The load at which a failure occurs.

Bridge-Lighting - A catwalk that crosses from one side of the stage to the other, used for lighting fixtures and operator access. It may be dead hung or flown.

Bridle - An assembly that splits a lift line into two separated attachment points. Used to support trusses or to provide extra support along a pipe batten to limit deflection.

Building Code - A set of municipal, stage, or federal guidelines for the design and construction of buildings.

Cable Clip - A device to mechanically fasten cables, consisting of bolts, nuts, and pads that bear against the cable to prevent crushing and slippage. Not recommended for permanent installation.

Cable Cradle - A device that supports an electrical cable loop and prevents sharp bends. It often has a hole for attachment of a lifting line.

Cable Reel - A drum for holding hose or various types of electrical cable that winds using springs or a motor. The hose or cable is connected at the hub of the drum so the connection to other systems is maintained as the drum rotates.

Cable Roller - A roller assembly designed to prevent moving cables from contacting any part of a building or adjacent rigging. Not intended to change cable direction or carry loads.

Capstan Winch - A winch, usually portable, with an un-grooved drum designed to assist in moving heavy loads. An operator wraps a rope around the drum and pulls to tighten the rope on the drum. Friction causes the rope to travel with the rotating drum.

Carriage - See "Arbor"

Catwalk - A walkway for access to a distant point (usually overhead).

Certificate of Occupancy - Certificate issued by a building inspector with local jurisdiction that certifies that a building meets codes and is safe to use.

Certified Rigger - A rigger who has passed the "Entertainment Technician Certification Program" (ETCP) exam and is recognized as competent to do rigging for a period of time. This certification is based on both experience and a written test. Regular re-certification is required.

Clew - Device that connects several ropes or cables to one, usually stronger, rope or cable.

Competent Person - The ESTA/ANSI Series E1 standards definition is a person who is capable of identifying existing and predictable hazards in the workplace, and who is authorized to take prompt corrective measures to eliminate them.

Contour Curtain - A brail or Austrian curtain rigged so that each lift line may be operated separately to form different shaped openings.

Counterweight - (n) Weights, usually flame cut steel or cast iron, that are placed in counterweight arbors to balance the weight of loads hung on battens. (v) The act of adding or removing weight from a set in order to achieve a balanced system.

Counterweight Arbor - See "Arbor"

Counterweight Assist Hoist - An electric hoist whose capacity is augmented by the addition of a counterweight arbor.

Counterweight Rigging - A rigging system where the load is balanced by a counterweight so that only a small force is required to overcome friction and move the load.

Counterweight Set - A single set (movable batten) in a counterweight rigging system.

Crash Rail - See "Stop Batten"

Cross Over - A hallway, outside of the stage house or behind the masking curtains, to allow performers and technicians to move from one side of the stage to the other without being seen.

CSI - Construction Specifications Institute

Curtain - Any fabric panel that is hung as part of a scene or to mask unwanted views.

Curtain Track - A formed or extruded shape that contains moving carriers and supports drapery. They often have a cord or other means to open and close the drapes.

Cyclorama - (1) Curtain at the rear of the performance area used to represent the sky or distant areas. (2) Set of borders, legs, and drops used to define the limits of a performance area.

D/d Ratio - The ratio between the tread diameter (D) of the drum or sheave and the cable diameter (d). Smaller ratios reduce the service life of cables.

Dash Pot - An adjustable, hydraulic ram that smoothly slows and stops a moving object.

Dead End - The end of a rope or part of a device that is not active or load carrying.

Dead Haul - Pulling a load that is not counterbalanced.

Dead Hung - Directly fixed to the structure or attached at a fixed elevation using chains, rods, or cable.

Dead Load - The permanent or non-removable part of a system load (i.e the weight of a batten versus the load hung from it).

Design Life - The minimum expected life of the system expressed in hours or cycles of operation.

Design Load - The load that a system or equipment item is designed to carry. This load can be made up of dead loads, live loads, dynamic loads, and environmental forces.

Direct Struck Limit - A limit switch that is actuated directly by a moving device passing by the switch location.

Diversity - A factor applied to power requirements for dimming and stage machinery. This reduces the amount of available power because it is very unlikely that all dimmers and stage machines will be in use, or at full power, at the same time.

Double Purchase - A rope or cable that passes from a lifting device (arbor, winch, or person) over a block, to a block attached to the load, and tied off at the previous block, is double purchased. The system allows twice as much load to be raised for a given effort, but the rope or cable must be pulled twice as far, so total work done remains the same.

Down Stage - The area of the stage that is closest to the audience. See "Raked Stage."

Drive Shaft - A rotating component that conducts power from an engine or other power source to a drum, pulley, or gear.

Drop Curtain - A curtain that is painted or constructed in a manner that makes it a part of the scenic environment.

Drum Hoist - A hoist with a drum for wrapping cable as it is taken up. One end of the drum is typically supported by a bearing while the other end is connected to the output shaft of the gear box.

Dynamic (Live) Load - The loads in a system that change in magnitude, direction, or location over time.

Egress - A path or walkway leading to an exit.

Electric - A name given to a pipe batten used to support lighting equipment in a theater.

Elevation - The height above or below an arbitrary point in a building (generally the stage floor).

Elevation Drawing - A drawing that shows the vertical face of an object or system.

Emergency Stop Circuit - This should be a fail safe, separately wired circuit in rigging control that stops any and all controlled machinery in an emergency. The circuit can be triggered by depressing Emergency Stop push buttons and by various automatic sensors and limit switches. To re-start it is necessary to take one or more specific actions to begin motion.

EN 362 - European Standard for personal protective equipment against falls from a height. Connectors.

Environmental Forces - Conditions in the environment which have an affect upon the strength, size, or effective life of equipment. Examples of forces include snow loads on roof and wind against the side of a building.

Equal Pitch - All grooves in the sheave have the same pitch diameter so that the center of each line travels the same distance as the sheave rotates one revolution.

ETL Link - Electro Thermal Links are fusible links which react (melt) when the ambient temperature reaches 165 degrees Fahrenheit or when subjected to an imposed electrical impulse.

Factor or Safety - The ratio between the rated working load of a component or system and its minimum ultimate breaking strength.

Fail Safe - A device or design that fails to a safe state. It does not mean that it will not fail.

Fail Safe Brake - A brake that will fully engage and resist motion of the device if power or control signal is lost. For example: a spring applied, electrically released brake.

Fall Arrest System - A device that engages to halt a person or other load that has exceeded a predetermined speed, indication a falling condition.

Field Check - A visit made to an installation project for the purpose or obtaining project measurements, checking its status, and finding potential conflicts.

Fire Safety Curtain - A curtain that closes automatically in event of a fire to prevent heat, smoke and flames on the stage from reaching the audience. The curtain may be closed when the space is not occupied to prevent unauthorized access and to prevent falls from the edge of the stage.

Fireline - Firelines are installed around the perimeter of a stage proscenium arch to hold the fire safety curtain open. Firelines connect the curtain to all manual electrical and heat activated devices that release the safety curtain.

Fixed Speed - A winch that operates at a single speed with no ability to modify speed. Fixed speed winches are typically used for low speed setup or heavy load applications.

Fleet Angle - The angle formed between the center line of a sheave or drum and another sheave or fixed point.

Floor Block - Pulley mounted at the floor to hold a rope or cable in position and to reverse its direction. Floor blocks meant for rope often incorporate a means of adjustment to accommodate changes in length due to loads or environmental conditions.

Flown - Suspended in a manner that permits the equipment to be raised and lowered.

Fly - The act of lifting scenery, lights, and curtains.

Fly Gallery - A gallery or catwalk above the stage floor from which counterweight and hemp (rope) rigging is operated.

Fly Loft - The space between the roof and the performance area that is not visible to the audience.

Forestage - The portion of the stage located in front of the proscenium or main curtain line.

Free End Ball - A heavy ball that is attached to the end of a fire line and wrapped around the fire safety curtain operating line to prevent closure of the curtain. When tension is released in the fire line the weight of the ball causes it to fall free, releasing the curtain.

Front Curtain (House Curtain) - A curtain used to define the stage location to the arriving audience. It is often the curtain closest to the audience and may also perform the function of an "Act Curtain."

Front of House (FOH) - A generic term for areas of the theater other than the stage, usually referring to the audience and lobby areas.

Fullness - Additional fabric that is added to a curtain to be sewn into pleats. 100% fullness means that the curtain would be double its finished width before the pleats are made.

Fusible Link - A device consisting of two metal parts that are soldered together. The solder melts at a predetermined temperature allowing the two halves to separate.

Gallery - Any platform above and to the side of the stage floor.

Gearmotor - The combination of a gearbox and motor in a single unit. The motor may also incorporate a brake.

Grade 5 Bolt - A medium carbon steel bolt that has been quenched and tempered for increased hardness and tensile strength in accordance with SAE Specification J429. The heads of bolts rated as Grade 5 have three lines at 120 degree intervals on their heads.

Green Room - A lounge for performers and/or technicians.

Gridiron (Grid) - An open floor, usually made from light steel channels or grating, that is located near the roof steel. It provides mounting locations for rigging equipment and access to that equipment for inspection and maintenance.

Guide - To control the movement of rigging devices by means of slides or rollers moving in tracks or on stretched cables.

Guide Shoe - A rolling or sliding device that connects a counterweight arbor or sliding tension block to guide rails in order to guide its travel.

Guide Rails - Components that confine and control the movement of counterweight arbors and tension floor blocks. See "J-Guide, A-Guide, Lattice Track, T-Guide, and Wire Guide."

Guillotine - A curtain that runs the width of the proscenium.

Hand Line - A line, usually rope, that is pulled by hand to lift or control the movement of a load.

Hand Winch - A device that consists of a hand crank that rotates a drum or pulley through a torque multiplying / speed reducing mechanism.

Head Block - A pulley mounted to support steel that changes the direction of lift and operating lines between the loft blocks and an arbor or winch.

Head Block Beams - Structural framing designed to support the head blocks and all related loads. Usually consisting of one or two beams and associated bracing members.

Heat Resisting Border - A curtain that is placed between stage masking curtains and a heat source, such as stage light, to prevent a fire. The heat resisting curtain employs a fabric which is fire proof, rated for high temperatures and spreads the heat from hot spots.

Hemp (Rope or Spotline) Rigging - A rigging system that employs ropes and sandbags instead if counterweight arbors or other devices. Usually used for temporary rigging.

Hoist - A geared mechanism, either hand operated or motorized, for use in raising (vertical movement only) equipment. The gearing produces a mechanical advantage in speed and load capacity.

Hoisting Machine - A powered machine used for raising, lowering, and holding objects.

Holding Brake - A brake used to hold a load in a static condition as opposed to decelerating a load to a stop and holding the load.

House - See "Auditorium"

House Curtain - See "Act Curtain"

House Left / Right - The sides of an auditorium as seen by an audience member while facing the stage.

HVAC - Air handling equipment in a building, consisting of Heating, Ventilation, and Air Conditioning.

Hydraulic Descent Control - A device used to control the speed of a closing fire curtain. These devices include hydraulic dampers, speed regulators, and dashpots.

IBC - The International Building Code. A model national building code that was created to replace regional building codes such as BOCA and UBC.

Idler - A pulley designed to support one or more cables but not to make direction changes.

Incremental Block - A multi-grooved pulley that supports and changes the direction of cables between the load and the head block and that supports other, more distant, lines in the set.

Index Light - A series of lamps in a special housing designed to illuminate the locking or pin rail area.

Index Strip - A device located at the front of a locking rail to hold line set identification labels.

J-Guide - J-shaped aluminum members fixed in parallel rows for the purpose of guiding arbors or clews.

Lattice Track - A parallel pair of angles or other structural members that guide an arbor or clew. Low friction slides or roller guides are placed on both sides of the device to be guided.

Lead Line - See "Lift Line"

Leg Curtain - A curtain used to define the side limit of the stage and to mask or hide actors, lights, and unused scenery in the off stage area (wings).

Lift Line - Any rope or cable located between a load and a winch or counterweight arbor.

Lighting Bridge - A walkway across the stage (fixed or flown) where lights are hung and where they may be adjusted and maintained.

Line Set - A system consisting of one or more lift lines and related components operating together to lift, lower, or suspend a load.

Limit Switch - An electro-mechanical switch that trips (changes state) when contacted by a moving device. They are used to halt the motion of a winch or other electro-mechanical device.

Line Shaft Winch - Winch with a series of cable drums connected to a gearbox by a common shaft.

Live End - The end of a rope or part of a device that is active or load carrying.

Live Load - The part of a system load that may be added or deleted (i.e. lights hung from a pipe batten).

Load Side Brake (Load Brake) - A brake in the power train of the winch that is attached to the same shaft as the load, at the output side of the gearbox.

Loading Gallery (Loading Bridge) - A gallery above the stage floor where technicians add and remove counterweights from the arbors. Usually located so technicians have access to arbors when battens are at their lowest positions.

Load Sensing - A mechanical or electrical device that senses the load in a cable or block and produce a signal that can be read by a controlling device.

Locking Collar - A fastening device located on the counterweight arbor rods above the upper spreader plate and counterweights and intended to help keep the weights in the arbor during a hard impact.

Locking Rail (Loading Rail) - A structural railing designed to support rope locks in a way that allows them to be easily operated. It holds the out of balance loads from the rigging system held by rope locks. It also serves as a safety railing for operators and other personnel.

Loft Block - A pulley mounted to the gridiron or support steel that supports and changes the direction of a lift line cable between the load and the head block.

Loft Well - (1) An opening in the gridiron designed for the attachment of loft blocks so that lift lines can pass through it. (2) An opening in the gridiron designed so cables can pass through from blocks mounted above without rubbing against the opening.

Loge - The part of a theater mezzanine closet to the stage.

Main Curtain - See "Front Curtain."

Masking - A set of curtains or scenic elements used to define the visual limits of a performance area.

MechanicBrakeal Systems - Equipment needed to make a building structure functional, including plumbing, fire protection, and HVAC.

Mezzanine - The lowest balcony in a theater.  

Motor (Primary) Brake - A brake that is mounted at the motor. It has a low torque capacity and fact response. used for normal stopping and holding duty on a motorized hoist.

Motorized Rigging - A theatrical rigging system using powered winches and other devices to move equipment rather than muscle power.

Mouse - To wrap the end of a rope, cable, or turnbuckle to prevent it from unwinding.

Mule Block - A pulley that supports and changes the direction of one or more cables traveling between loft blocks and head block.

Mule Winch - See "Capstan Winch."

Multi-Cable - Electrical cable with multiple conductors that conducts electrical power to multiple circuit wire ways and boxes on stage. At least one conductor must be used as a grounding wire.

Multi-Line Block - Any block that can support more than one line. See "Incremental Block" and "Multi-Sheave Block."

Multi-Sheave Block - A block with more than one sheave, each of which can support and change the direction of a rope or cable. Sheaves can be held by common shaft or by multiple shafts within a common housing.

NEC - The National Electrical Code (USA)

NEMA - National Electrical Manufacturers Association

NFPA 101 - The Life Safety Code

Nicopress - A registered trademark of the National Telephone Supply Company, used to describe compression type sleeves placed at the end of a wire rope to interconnect two ropes or to form an eye at the end.

Off Stage - The stage floor area that is not a part of the acting area and is not visible to the audience.

Olio Stage - A curtain located between the "Front" or "Act" curtains and the "Rear" curtain that closes off a portion of the acting area for more intimate presentations. It is often colored or decorative.

On Stage  -  The portion of the stage area visible to the audience, usually defined by masking curtains, scenery, and orchestra shell, or by lighting.

Orchestra - (1) A group of musicians who play instrumental selections (2) The portion of the auditorium on the main floor that is closest to the musicians and the acting area.

Orchestra Lift - A moving platform that is used to adjust the elevation of the musicians in relation to the stage and auditorium. Usually operates within the confines of an orchestra pit.

Orchestra Pit - A depressed area between the stage and audience seating area where musicians sit, so the audience can hear the music and see the performance over the heads of the musicians.

Orchestra Pit Filler - Removable platforms that are used to close off the orchestra pit at the level of the stage or auditorium.

Orchestra Pit Lift - A section of the orchestra pit floor that may be raised and lowered by some mechanical (typically motorized) means.

Orchestra Shell - An enclosure on stage, consisting of walls and a ceiling that reflects sound into the auditorium. Usually decorative in nature.

Over Balance Bar System - In this system the curtain and counterweight are balanced so the the curtain can be raised and lowered manually with minimum effort. A weighted bar is held above the upper batten of the fire safety curtain by a hinged mechanism. The hinged mechanism opens when the fire line is released, so that the weighted bar slides down the center lift lines to rest on the upper batten. This makes the curtain heavier than the counterweight and causes it to close.

Over Speed Brake - And brake that is setup to recognize when the speed exceeds a preset threshold and then acts to stop the controlled load.

Out of Balance - A condition that exists when the weight of a batten, fittings, and attached loads do not equal that of counterbalancing equipment such as counterweight and an arbor. For safe and efficient use, manually operated sets should be balanced to within 50 pounds of neutral.

Outrigger - A barrier device that protects counterweight arbors from scenery, etc. that may be leaned against them. Often, also supports index lights.

Paint Frame - A rigid frame, usually made of wood, to which drops and flats may be attached vertically for painting. They are normally rigged to be raised and lowered so painters can reach all areas of the frame.

Parking Brake - See "Holding Brake."

Pendant - A hand held controller that is attached to an electrical cable so the operator can move about to obtain better visibility of the devices being controlled.

Pileup Winch - Winch with a drum that has a narrow slot to contain the cable in a single vertical layer. The speed and load capacity varies with each layer of cable. Also called a Yo-Yo winch.

Pinrail - A railing with holds to accept belaying pins. May also act as a safety railing at the edge of a gallery or walkway.

Pipe Clamp - Clamping device that bolts around a pipe for attachment of chain or cable hangers.

Pipe Grid - Horizontal structure hung over a stage or auditorium to support lights and scenery. Made from pipes crossing on right angles at set intervals.

Pipe Weight - The counterweight needed in an arbor to keep an empty batten evenly balanced.

Pitch Diameter - Diameter of a sheave or drum measured from the center line of the cable wrapped around it.

Pivot Block - A pulley designed to adjust to structures at odd angles.

Plan Drawing - A drawing that shows the layout or top view of a construction or object.

Point Hoist - A single line winch, used singularly or in groups, to hold a load at a specific point over the stage. They are the motorized equivalent of spot lines, providing the greatest flexibility possible in automated rigging (Similar to a dimmer per circuit in lighting.)