Keyholder or Cardholder
A person who carries an ID device. Two types of key/card holder exist: i. Personnel - usually a tenant or full time employee. ii. Visitor - a contractor or other person who requires some access around the site, but for a limited number of days only.

Latchbolt
A device for automatically retaining a door in the closed position upon its closing. 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 bold projects into a hold provided in the strike, holding the door in a closed position.

LED
Light Emitting Diode. A semiconductor device that emits light.

Locking Device
The most usual locking devices used in the access control industry are electric strikes and electro-magnetic locks. To select which locking device should be used on a specific job, the installer must proceed to an evaluation that will take into account not only the security requirements but also the regulations imposed by local or national authorities. Simple rules for most cases: Rule #1: If possible, always use electric strikes on controlled doors (doors equipped with at least one reader). Rule #2: Add an electro-magnetic lock if you want to prevent exit through that door or to control exit with a card reader or a keypad. Note that we are adding an electro-magnetic lock and keeping the door strike. This is necessary to keep the door locked and the premises secured when the electro-magnet lock has to be unlocked because of an AC power failure or a fire alarm signal (see regulations). Rule #3: Always check with local authorities before installing any electro-magnetic lock. Once installed, it can be quite expensive to replace maglocks by strikes and repair doors and door frames. Other hardware: The outside door knob (or handle) should be permanently locked. It is always the access controller that will unlock the door by releasing the door strike. The inside door knob should always be free (unlocked) to permit safe exit to occupants in case of emergency. To prevent the door from being left manually unlocked, make sure there are no lock-unlock buttons on the inside door knob. An hydraulic door closer is almost mandatory to insure that the door is re-closed after an entry and to prevent "Open Too Long" or "Door Left Open" alarms. 

Magnetic Stripe
The black or brown stripe that you see on your credit card, airline ticket or access card. The stripe is made up of tiny magnetic particles in a resin. The magnetic property of the stripe allows it to be encoded with a number of bits. In access control this data would include a facility code and card number. Card technology that uses a Magnetic Stripe to hold its data. System 2 uses a track 2 ABA format.

Man Trap
A method used to provide strict access control by preventing access at one specified entrance while another entrance is being utilized. Typically two doors, separated by an enclosed spaced, are interlocked. When one door is opened the second door is incapable of being opened.  

Mapping (or memory map)
A functional representation of the different memory blocks.

Master
A system unit, programmed to be part of a network of systems and in control of "slaves" on the network.

Matching
The comparison of biometric templates to determine their degree of similarity or correlation. A match attempt results in a score that, in most systems, is compared against a threshold. If the score exceeds the threshold, the result is a match; if the score falls below the threshold, the result is a non-match.

Matrix Switch
A video switcher that provides a scalable number of video inputs and monitor outputs, allowing routing of any available input signal to any output signal (crosspoint switching). Matrix switchers are usually located at a security operations center where all video concentrates and will display on multiple monitors. Users control the matrix via a joystick keyboard that allows switching and pan tilt zoom control of domes.

Memory Card
A chip card with memory, but controlled only by fixed logic rather than by a microprocessor.

Minutiae Points
Local ridge characteristics that occur at either a ridge bifurcation or a ridge ending.

Multi-application Card (or general purpose card)
A smart card that can accommodate more than one application while maintaining separate security conditions.

Multi-site
A system which allows more than one group of door controllers on different sites (even in different countries) to be administered from the same central location.

Multos
A programming language developed by Mondex for systems using MAOS (multi-application operating systems) for smart cards.

Networking
The ability of system's to be linked together. A multi-drop, twisted pair of wire is connected to each system unit in the network in a daisy-chain fashion