Martian-MDA

Martian

Packets that turn up unexpectedly on the wrong network because of bogus routing entries. Also used as a name for a packet which has an altogether bogus (non-registered or ill- formed ) Internet address.

Martian Mail

An email message that arrives months after it was sent (as if it had been routed via Mars).

Martian Packet

Strange fragments (data packets) of electronic mail that turn up unexpectedly on the wrong computer network because of bogus routing. Also used for a fragment that has an altogether unregistered or ill-formed Internet address.

MAS

1. Minimum Average Surcharge.

2. Mobile Application Subsystem. An MAS is application software that is independent of the Cellular Digital Packet Data (CDPD) network. A cellular radio term .

3. Multiple Address System. A microwave point-to-multipoint communications system, either one-way or two-way, serving a minimum of four remote stations . The private radio MAS channels are not suitable for providing a communications service to a larger sector of the general public, such as channels the commission has allocated for cellular paging or specialized mobile radio services. (SMR).

MASC

1. Major Accounts Service Center.

2. Major Account Support Consultant.

MASER

Microwave Amplification by Stimulated Emission of Radiation. A device that generates electromagnetic signals in the microwave range, known for relatively low noise.

Mask

1. A field made up of letters or numbers and wildcard characters , used to filter data. For example, a mask 800xxxxxxx may be applied to the dialed digits field of a call record to identify toll-free calls.

2. A computer imaging term. The electronic equivalent of placing transparent tape over selected regions of an image, a mask marks pixels that remain unchanged by subsequent painting operations. For example, you might mask out a mountain range and add background clouds to the sky. In the final image, the clouds will appear between the peaks.

Maskable Interrupt

An interrupt on a computer that can be interrupted by another interrupt.

MASP

Mediated Attribute Store Protocol, an XML-based protocol for a new attribute store service.

MASQ

See IP Masquerade and Masquerade.

Masquerade

1. To pretend to be someone else by using another person's password or Token. It's not a nice thing to do.

2. See IP Masquerade.

MASS

Major Account Support Specialist.

Mass Splicing

Simultaneous splicing of many fibers in a cable.

MASS860

An organization of computer system vendors formed to promote open system standards and the writing of applications software for the Intel i860 microprocessor. Members include Intel, Oki Electric Industry Co., Ltd., IBM, Stratus, Olivetti, Alliant, Samsung and Stardent Computer.

Massively Parallel Systems

Tightly coupled multi processing computers that house 100 or more CPUs, each with its own memory.

Mast

A pipe or pole used for mounting antennas.

Mast Clamp

A piece of equipment used to attach a ram hook to a pole. Aerial service wire is attached with a ram hook (sometimes called a ram horn) with a drop clamp.

Master

Term applied to the data communications equipment at one end of a synchronous digital transmission network that supplies the clock timing signal that determines the rate of transmission in both directions.

Master Address Street Guide

MSAG. In the emergency services telephone network in the United States, the Master Address Street Guide is a database containing the mapping of street addresses to Emergency Service Numbers within a given community. This allows the derivation of call routing information from a call's Automatic Location Identification. See Automatic Location Identification.

Master Clock

An electronic timing circuit which synchronizes the entire data communications network. The source of timing signals, or the signals themselves , that all network stations use for synchronization.

Master Control Program

A part of the Burroughs operating system that monitors the host's operation.

Master Control Unit

MCU. An InteCom word for the device which controls the main operating functions of the system.

Master Customer Number

MCN. A Verizon definition. A unique number that identifies a customer. Also known as Customer Identification Number.

Master Frequency Generator

In FDM, equipment used to provide system end-to-end carrier frequency synchronization and frequency accuracy of tones over the system.

Master Group

MG. In frequency division multiplexing (the old way of putting many voice conversations onto on communications line) a master group consists of 300 voice- grade (4 kHz) channels.

Master Number Hunting

When a call is directed to the pilot number of a hunt group, it will hunt to the first non-busy station in that group. If a call is directed to a specific station in that hunt group it will go directly to that station and not hunt to another station in the group.

Master Slave Switching System

A configuration consisting of a central switch and one or more remote switches. The master switch typically controls all I/O (input/output) information. The slave system performs tasks as directed by the master, including switching calls between phones attached to that remote module ” without sending those calls back to the central switch. There are enormous savings in wiring since not every remote phone has to have a pair back to the central switch.

Master Slave Timing

In a communication system, a timing subsystem wherein one station or node supplies the timing reference for all other interconnected stations or nodes.

Master Station

1. The main phone or station in a group. The one controlling the transmission of the others.

2. The unit which controls all the workstations on a LAN, usually through some type of polling. The master station on a token-passing ring allows recovery from error conditions, such as lost, busy or duplicate tokens, usually by generating a new token. Sometimes servers are referred to as master stations.

3. In navigation systems employing precise time dissemination , a station whose clock is used to synchronize the clocks of subordinate stations.

4. In basic mode link control, a data station that has accepted an invitation to ensure a data transfer to one or more slave stations. At a given instant, there can be only one master station on a data link.

Mastergroup

MG. 10 supergroups each comprised of 5 groups of 12 channels summing up to 600 circuits transported as a unit in an analog FDM carrier system. First used in Bell's type L1 carrier systems on intercity coaxial cable. Six mastergroups are equal to one jumbogroup.

Masters of Deception

A group of young people who gained notoriety of sorts by hacking and cracking the U.S.'s telephone system, securing free phone calls and gaining admission to networked computer systems. There were two rival groups, the Masters of Deception and The Legion of Doom. They attempted to outdo each other with greater and greater feats. The leader of the MOD was a fellow who called himself Phiber Optik. Michele Slatalla and Joshua Quittner wrote a book chronicling the whole story. It's called Masters of Deception; The gang that rule cyberspace .

MAT

Meridian Administration Tools.

MATC

Major Account Technical Consultant.

Matched Junction

A waveguide component having four or more ports, and so arranged that if all ports except one are terminated in the correct impedance, there will be no reflection of energy from the junction.

Matching Loss

ML. A telephone company definition. The inability to find an idle path between two idle equipment components . Usually expressed as a percentage. Example: Incoming Matching Loss, Originating Matching Loss, etc.

Mated Pair

1. A pair of devices which are perfectly matched. In other words, they perform identical functions. Modems, for instance, are perfectly mated as they perform the same functions of modulating and demodulating signals, depending on the direction of the transmission. Otherwise, they can't communicate. Like most things in network technology (and most things in life) communications is best accomplished between entities that are balanced and symmetrical. By the way, two mated pairs of things are known as " quads ."

2. If you move out of a residential apartment, the pair that you were using is dedicated to that Apt. so when the next occupant moves in, it is a flick of a switch to get phone service turned on. That's called Dedicated Pair Out (DPO). The DPI pair is the OE (Office Equipment) or the Switch pair. Now the pair in the C.O. (Central Office), when it's joined to the DPO pair, is often called a mated pair. The DPI pair is mated to the DPO pair.

MATEL

A Multiplex Automatic TELephone system. Picture one long, up to two miles wire (any decent quality works). You roll it out, then you clip phones anywhere into the wire. Then you have, in effect, a seven channel bus PBX. You have two digit extension dialing between the phones (up to 60). You also have conferencing, broadcast, call back, DID and connection to one central office line and one radio channel. The uses? String it around a rioting prison , a siege, an airport hijack , an emergency in New York City subway , etc. Three advantages: instant communications, communications where radio is bad and radio silence ” you keep the press and the bad guys in the dark. This definition from John McCann, general manager of Racal Acoustics Limited, Frederick, MD, which makes the MATEL.

Material Dispersion

Material dispersion occurs because of pulse of light in a fiber includes more than one wavelength. Because of the refractive index of a material varies with wavelength (check out a prism in the sun!) different wavelengths travel down the fiber at different paths. See also Chromatic Dispersion.

Material Scattering

In an optical fiber, that part of the total scattering attributable to the properties of the materials used for fiber fabrication.

Math Coprocessor

A coprocessor is a special purpose microprocessor which assists the computer's main microprocessor in doing special tasks. A math coprocessor performs mathematical calculations, especially floating point operations. Math coprocessors are also called numeric and floating point coprocessors . If you do a lot of mathematical tasks on your PC, like recalculating large spreadsheets, then installing a math coprocessor makes huge sense. Intel included a math coprocessor with its 486DX chip, but removed it for the 486SX. No other Intel chip has a math coprocessor built in. When you buy a math coprocessor make sure it's the same speed as your existing processor.

MATR

Minimum Average Time Requirement.

Matrix

1. A switch. A device for moving calls from one input to the desired output. There are many types of switching matrices ” from simple step-by-step matrices to complex digital pulse code modulated matrices. Most switching matrices are "blocking." They do not have sufficient capacity to switch every call. There are some switches that are "non- blocking." These have the ability to switch every call simultaneously . By definition, nonblocking matrices are more expensive. They are only needed in special situations of high traffic.

2. The encompassing material in the composite (i.e. the plastic).

Matrix Ringing

Two key system phones picking up the same extensions with different lines ringing on different phones. These days, with electronic phones, matrix ringing is easy. In the old days, with 1A2 phones, you needed to do considerable wiring.

Matrix Switch

Device that allows multiple channels connected via serial interfaces (typically RS-232C) to connect under operator control to designated remote or local analog circuits or other serial interfaces.

Matthews, Gordon

February, 23, 2002. AUSTIN - Gordon Matthews, the inventor of voice mail, died Saturday from complications related to a stroke. He was 65. Matthews was the holder of more than 35 U.S. and foreign patents ” including the one for voice mail. Matthews first conceived the technology known as voice mail in the late 1970s and patented it in 1982. The success of his "Voice Message Exchange" in a digital format and manipulating electronic messages gave birth to a new industry. "I'm not really pleased with some of the things I see voice mail being used for today," Matthews once said. "We didn't design this technology to annoy people, but rather make their lives easier." Matthews attended the University of Tulsa, where he studied engineering physics. After graduating in 1959, Matthews joined the Marines as an aviator, in honor of his uncle and his father, who also was a Marine. He discovered his desire to invent when a friend was killed in a midair collision. It was believed that he had to momentarily take his hands off the controls to adjust his radio frequency. Five years later, he traded in his uniform to work in a suit at IBM Inc., where he developed a system that allowed pilots to control cockpit functions with their voice. "Every one of my inventions came about when something bothered me," he once said in an interview. He believed that if a solution can be envisioned , it also can be created. He moved to Dallas in 1966 to work for Texas Instruments. He specialized in using computers to automate telephone systems of large corporations with multiple lines and then launched a series of his own businesses specializing in computers and telecommunications. In 1979, Matthews formed a new company, VMX Inc. of Dallas, which stands for Voice Message Express. Matthews applied for a patent in 1979 for his voice mail invention and sold the first system to the 3M Corp. in Minnesota in 1980. His wife, Monika, recorded the first greeting on this first commercial voice mail. By 1989, his company was earning royalties of what he said were "tens of millions of dollars." But he knew it was time to sell. "The market was growing faster than I could grow the company," Matthews once said. He sold VMX Inc. and retired to Austin after 13 years with his Dallas-based voice mail company.

MATV

Master Antenna System, such as used in apartment buildings and motels.

MAU

1. Math Acceleration Unit.

2. Multistation Access Unit. A MAU is a wiring concentrator used in Local Area Networks. In token ring networks it's called a MultiStation Access Unit (MSAU). In Ethernet networks it's called a Medium Attachment Unit. Basically a MAU is a standalone device that contains multiple NICs (Network Interface Cards), thereby allowing multiple terminals, PCs, printers, and other devices to be share a single point of connection to a Token Ring or Ethernet LAN. Each computer is wired directly to the MAU which then provides the connection to the LAN.

MAUs themselves can be connected to expand the network. The MAU is a small box with eight or sixteen connectors and an arrangement of relays that function as bypass switches. When only one MAU is used, its relays and internal wiring arrange themselves so that the MAU and the connected computers form a complete electrical ring. MAUs can be cascaded to create bigger rings. The MAU listens for the "I'm here" signal sent by a computer when the computer is attached to the MAU. If the token ring adapter card in a computer is not working properly or the computer is turned off, the MAU no longer hears the "I'm here" signal and automatically disconnects the computer from the ring using the bypass relay.

Maverick Buying

See B2B.

MaxCR

Maximum Cell Rate: This is the maximum capacity usable by connections belonging to the specified service category.

Maximize Button

The maximize button in Windows is the up-arrow button at the far right of a title bar in the Windows operating system. Click on the maximize button to enlarge the IMARA Lite window to full size . See also, Minimize button and Restore button.

Maximum Access Time

Maximum allowable waiting time between initiation of an access attempt and successful access.

Maximum Block Transfer Time

Maximum allowable waiting time initiation of a block transfer attempt and completion of a successful block transfer.

Maximum Burst

Specifies the largest burst of data above the insured rate that will be allowed temporarily on an ATMPVC but will not be dropped at the edge by the traffic policing function, even if it exceeds the maximum rate. This amount of traffic will be allowed only temporarily; on average, the traffic source needs to be within the maximum rate. Specified in bytes or cells . See Maximum Burst Size.

Maximum Burst Size

MBS. ATM network performance parameter that defines the duration of transmission at a peak rate that would be accepted on a given ATM virtual circuit. See Maximum Burst.

Maximum Calling Area

Geographic calling limits permitted to a particular access line based on requirements for a particular line.

Maximum Keying Frequency

In facsimile systems, the frequency in hertz numerically equal to the spot speed divided by twice the X-dimension of the scanning spot.

Maximum Modulating Frequency

The highest picture frequency required for a given facsimile transmission system. The maximum modulating frequency and the maximum keying frequency are not necessarily equal.

Maximum Power Level

Maximum power output limit for Mobile end System (M-ES).

Maximum Rate

Maximum total data throughput allowed on a given virtual circuit, equal to the sum of the insured and uninsured traffic from the traffic source. The uninsured data might be dropped if the network becomes congested . The maximum rate, which cannot exceed the media rate, represents the highest data throughput the virtual circuit will ever deliver, measured in bits or cells per second.

Maximum Stuffing Rate

The maximum rate at which bits can be inserted or deleted.

Maximum Transmission Unit

MTU. The largest possible unit of data that can be sent on a given physical medium. Example: The MTU of Ethernet is 1500 bytes.

Maximum Usable Frequency

MUF. The upper limit of the frequencies that can be used at a specified time for radio transmission between two points and involving propagation by reflection from the regular ionized layers of the ionosphere. MUF is a median frequency applicable to 50 percent of the days of the month, as opposed to 90 percent cited for the lowest usable high frequency (LUF) and the optimum traffic frequency (OTF).

Maximum User Signaling Rate

The maximum rate, in bits per second at which binary information can be transferred (in a given direction) between users over the telecommunication system facilities dedicated to a particular information transfer transaction, under conditions of continuous transmission and no overhead information.

Maximum Viewing Area

In a glass cathod ray tube monitor, the maximum viewing area is the actual maximum viewing area and it is dependent upon the size of the plastic or bezel around the CRT.

Maybe

"I'll give you a definite maybe." Samuel Goldwyn, film producer. See Goldwyn.

MAYPAC

A X.25 packet-switched network operated in Malaysia by the Malaysian government.

MB

Megabyte. A unit of measurement for physical data storage on some form of storage device ” hard disk, optical disk, RAM memory etc. and equal to two raised to the 20th, i.e. 1,048,576 bytes. Here is a summary of sizes:

MB = Megabyte (2 to the 20th power)

GB = Gigabyte (2 to the 30th power)

TB = Terabyte (2 to the 40th power)

PB = Petabyte (2 to the 50th power)

EB = Exabyte (2 to the 60th power)

ZB = Zettabyte (2 to the 70th power)

YB = Yottabyte (2 to the 80th power)

One googolbyte equals 2 to the 100th power.

Mbaud

One million bits of information per second. Also referred to as Mbps or Mb/s.

MBG

Multilocation Business Group.

Mbits

Million bits. See Mbps.

MBONE

Multicast Backbone. A collection of Internet routers that support IP multicasting. The MBONE is used as a "broadcast (actually multicast) channel" on which various public and private audio and video programs are sent. Circa 1992 IETF (Internet Engineering Task Force) effort. Came out of earlier ARPA DARTnet experiments. Supports multicast audio and video across the Internet. Provides one-to-many and many-to-many network delivery services for apps like videoconferencing and audio. Supports simultaneous communication between several hosts . At present, the Internet MBONE is the largest demonstration of the capabilities of IP Multicast. The MBONE is an experimental, global, volunteer effort, and topographically is layered on top of portions of the physical Internet. (IP multicast packet routing is not supported by many installed production routers.) The network is linked by virtual point-to-point links called "tunnels". The tunnel endpoints are typically workstation-class machines having operating system support for IP multicast and run the "mrouted" multicast routing daemon. It presently carries IETF meetings, NASA space shuttle launches, music, concerts, and many other live meetings and performances . www.mbone.com.

Mbps

This one is confusing. When you see Mbps as the speed of a telecommunications, networking or local area networking transmission facility (i.e. something that moves information), Mbps means million bits per second ” exactly one million. No more. No less.

When you see Mbps or MBps referred to the context of computing, it means million bytes per second, which is the same as one million bytes per second. How many bits that is depends on how many bits there are in a byte. Typically it's eight (but it could be more or fewer). So, in this case, one Mbps would be eight million bits per second.

To be correct, Mbps is million bits per second and MBps is million bytes per second. You will also see it written as Mb/s. That usually means million bits per second. For a much longer explanation, see Bps.

MBS

1. Maximum Burst Size. An ATM term for a traffic parameter which specifies the maximum number of cells which can be transmitted at the Peak Cell Rate (PCR). In the signaling message used for call setup, the Burst Tolerance (BT) is conveyed through the MBS. The BT, together with the SCR and the GCRA, determine the MBS that may be transmitted at the peak rate and still be in conformance with the GCRA.

2. Meridian Business Set.

MBus

A Sun Microsystems definition: An open specification for connecting multiple CPUs (such as those in SPARC modules) with a 64-bit, 320-MB/second data path. Designed by Sun Microsystems; available from SPARC International.

MBWA

Management By Walking Around. A technique pioneered by David Packard, one of the two founders of Hewlett-Packard which he and Bill Hewlett started in 1939 in a small garage in Addison Avenue in Palo Alto, CA.

MBZS

Maximum Bandwidth Zero Suppression.

MC

1. Main Cross-connect. The interconnect point where wiring from the entrance facility and from the workstation is connected to telecom equipment.

2. Matrix Controller.

3. Multi-Carrier.

MC1 Cable

The inter-PC chassis MVIP bus cable, which can support up to 20 PCs. It allows a developer to distribute MVIP's resources across all the connected computers. MCMVIP type MC1 media provides 1536 x 64 Kbps of inter-chassis connectivity using twisted-pair copper cables. See MC2 and MVIP.

MC2 Cable

The advanced inter-PC chassis MVIP bus cable, which leverages FDDI-II to provide up to 3072 x 64 Kbps of inter-chassis connectivity on fiber or copper. MC3 leverages SONET/SDH fiber technology at 155 Mbps to provide 2400/4800 x 64 Kbps of inter-chassis telephony. See MC1 and MVIP.

MC-MVIP

Multi-Chassis MVIP. See MVIP.

MCA

Micro Channel Architecture. The internal 32-bit bus inside some of IBM's PS/2 machines. It was originally introduced by IBM as a proprietary bus which manufacturers of IBM clone PCs would have to pay IBM large royalties if they wanted to include the bus in their machines. Sadly, this strategy backfired and few people wanted IBM PCs with the MCA bus. ISA remains the most popular PC bus. See ISA and EISA.

MCC

1. Mobile Country Code. A portion of the LAI and the IMSI (International Mobile Subscriber Identity).

2. Mobile Control Channel. See Control Channel.

MCCS

Mechanized Calling Card Service was formerly known as ABC Service. MCCS is a CO switch facility that automatically bills credit card calls made on DDD without the involvement of an operator.

MCDV

An ATM term. Maximum Cell Delay Variance: This is the maximum two-point CDV objective across a link or node for the specified service category.

MCF

Message Confirmation Frame. Confirmation by the receiver in a fax transmission that the receiver is ready to receive the next page.

McGill, Archie

See Dimension.

MCHG

Mass Change.

MCHO

Mobile Controlled Hand-off.

MCI

1. Once upon a time it was called Microwave Communications Inc. Then it became just MCI, which stands for nothing. MCI was the largest long distance phone company in the US after AT&T. In MCI's early days, the initials were said to stand for "Money Coming In." MCI was a full-service long distance company offering every service from switched single channel voice to leased T-1. In 1996, it announced that it had accepted a takeover offer from British Telecom (BT), the leading phone company in England. BT had held a 20% stake in MCI for a number of years, and viewed MCI as a vehicle to gain a significant position in the highly lucrative U.S. market. Then GTE offered more. Then upstart Worldcom offered even more. The MCI/Worldcom merger was completed on September 20, 1998 for approximately $40 billion (not cash, but shares). MCI Worldcom, at the time of the merger, boasted annual revenues of $30 billion, and a presence in over 65 countries . In order to gain regulatory approvals in the U.S. and Europe, MCI sold its Internet backbone to Cable & Wireless for $1.75 billion. See also Worldcom.

2. Media Control Interface. A standard control interface for multimedia devices and files. Using MCI, a multimedia application can control a variety of multimedia devices and files. Windows provides two MCI drivers; one controls the MIDI sequencer, and one controls sound for .WAV files.

3. Message Center Interface. An interface in some PBXs which allows you to connect an external PC and do voice mail/IVR (interactive voice response).

MCI Worldcom

The company formed on September 20, 1998, when Worldcom merged with (read acquired ) MCI for approximately $40 billion. MCI Worldcom, at the time of the merger, boasted annual revenues of $30 billion, and a presence in over 65 countries. In order to gain regulatory approvals in the U.S. and Europe, MCI sold its Internet backbone to Cable & Wireless for $1.75 billion. Now it's simply called Worldcom. See also MCI and Worldcom.

MCL

Mercury Communications Limited (UK). The second long distance company in England. It is competitor of British Telecom, the erstwhile monopoly local and long distance company in the U.K.

MCLD

Modifying Calling Line Disconnect. This is what CPC (Calling Party Control) is referred to on the Lucent 5ESS switch. See Calling Party Control.

MCLR

An ATM term. Maximum Cell Loss Ratio: This is the maximum ratio of the number of cells that do not make it across the link or node to the total number of cells arriving at the link or node.

MCN

See Master Customer Number.

MCNC

Microelectronic Center of North Carolina.

MCNS

Multimedia Cable Network System Partners Ltd. An organization which is leading the development of DOCSIS (Data Over Cable Service Interface Specification), which is an industry specification that defines the technical equipment and interface specifications for high-speed cable modem and headend equipment in order to deliver high-speed data services over cable television systems. MCNS consists of Comcast Cable Communications Inc., Cox Communications, Tele-Communications Inc. (TCI), and Time Warner Cable. MCNS has partnered with a number of other companies in this project, as well. See also DOCSIS.

McNutt, Emma M.

The first female telephone operator, Ms. Emma M. McNutt was hired in September 1878 by the New England Telephone company in Boston, Massachusetts. Her hiring caused quite a stir, as "proper ladies" didn't work outside the home in those days. Previous to Ms. McNutt's appearance on the scene, all of the operators were males, who proved themselves to be unruly. Within a few short years male operators were extinct ” for about 100 years, at least. Ms. McNutt worked for the Bell System until her retirement in 1911.

MCP

Master Control Program. A part of the Burroughs operating system that monitors the host's operation.

MCR

An ATM term. See Minimum Cell Rate.

MCRIS

See Message Customer Record Information System.

MCSE

Microsoft Certified Systems Engineer.

MCSP

Microsoft Certified Solutions Provider.

MCT Algorithm

A compression algorithm introduced in 1986 by PictureTel. MCT reduced the bandwidth necessary to transmit acceptable picture quality from 768 kbps to 224 kbps making two-way videoconferencing convenient and economical at relatively low data rates (for those times).

MCTD

An ATM term. Maximum Cell Transfer Delay: This is the sum of the fixed delay component across the link or node and MCDV.

MCU

Multipoint Control Unit. A bridging or switching device used in support of multipoint videoconferencing and supporting as many as 28 conferenced sites. The devices may be in the form of CPE or may be embedded in the WAN in support of carrier-based videoconferencing services. MCU standards are defined in ITU-T H.231, with T.120 describing generic conference control functions.

MCVF

MultiChannel Voice Frequency.

MD

1. Mediation Device. A SONET device that performs mediation functions between network elements and OSs. Potential mediation functions include protocol conversion, concentration of NE to OS links, conversion of languages, and message processing.

2. Manufacturer Discontinued. A product that the manufacturer no longer makes is called "manufacturer discontinued." Some people think it's a nice way of saying obsolete. But there are many "obsolete" products that do just fine, often for less money. And I personally find that every time I fall in love with a product and want to buy another one, it's "manufacturer discontinued."

3. Message Display.

4. Message Digest. Refers to a message digest function, or algorithm, used for digital signature applications in the Internet. See also Digital Signature and MD5.

MD5 Algorithm

Message-Digest (version) 5 Algorithm. As defined in RFC 1321 from the IETF (Internet Engineering Task Force), MD5 is an algorithm which takes an input message of arbitrary length, and produces an output in the form of a 128-bit " fingerprint " or "message digest." The algorithm is intended for digital signature applications, where a large file must be compressed in a secure manner before being encrypted with a private key under a public-key algorithm such as RSA. It is conjectured that it is computationally infeasible to duplicate an MD5 message, or to produce any pre-specified MD5 message. The Message-Digest function also is known as a one-way hash function. See also Compression, Digital Signature, Encryption, Hashing, Private Key, Public Key, and RSA.

MD-IS

Mobile Data Intermediate System.

MD-IS Serving Area

A cellular radio term. The set of cells controlled by a single serving Mobile Data Intermediate System.

MDA

Monochrome Display Adapter.