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MMAC (Media Access Control): A media-specific access control protocol within IEEE 802 specifications; currently includes variations for Token Ring, token bus, and CSMA/CD. It is IEEE's lower sublayer of the OSI link layer. See also Logical Link Control (LLC). MAC Address: The 48-bit address block of a device used at the data link layer. See MAC. Ethernet hardware addresses are 48 bits, expressed as 12 hexadecimal digits (0-9, plus A-F, capitalized). These 12 hex digits consist of the first/left 6 digits (which should match the vendor of the Ethernet interface within the station) and the last/right 6 digits which specify the interface serial number for that interface vendor. These high-order 3 octets (6 hex digits) are also known as the Organizationally Unique Identifier or OUI. Ethernet addresses should be written hyphenated by octets (e.g., 12-34-56-78-9A-BC). These addresses are physical station addresses, not multicast nor broadcast, so the second hex digit (reading from the left) will be even, not odd. The IEEE assigns Ethernet block addresses. Ethernet numbers at IANA. Mail Gateway: A machine that connects to two or more electronic mail systems (especially dissimilar mail systems on two different networks) and transfers mail messages among them. Mail Path: A series of machine names used to direct electronic mail from one user to another. Mail Reflector: A special mail address; electronic mail sent to this address is automatically forwarded to a set of other addresses. Typically, used to implement a mail discussion group. Mailing List: A possibly moderated discussion group, distributed via email from a central computer maintaining the list of people involved in the discussion. MAN (Metropolitan Area Network): is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network. Management Information Library: A document containing the specification of all defined managed objects and a complete description of their behavior. Development of this library is currently being proposed by groups such as the NIST OSI Implementers' Workshop Group. Management Information: The set of managed objects in a system, together with their attributes, constitutes that system's management information base. It is a conceptual repository of management information at each system. Marginal Capacity Cost (MCC) - measures the cost of capacity associated with the unit that would be added, or the resources rights that would be purchased, to serve incremental load. MCC usually is measured in reference to additions to system peak loads, in terms of dollar per kilowatt of additional capacity added. Marginal Energy Cost (MEC) - the variable generation operating cost incurred to serve an incremental unit of load, or the cost saved from an increment in load reduction. Convention measures energy costs in dollars per kilowatt-hours. As a marginal measure, its level is dependent upon the load level from which the increment is measured, and the size of the increment. In its strictest interpretation, the increment is one kW(h). In practice, the models and methods employed to estimate or measure MEC require a larger increment of load change, often as large as 10 megawatts, more which exceeds the total load of all but a few customers. Therefore, MEC is an illustrative and generic measure that in practice cannot be associated directly with the actions of any one customer. The point on the demand for electricity curve where MEC is measured is a function of the purpose at hand. For RTP, that measurement is taken at the level of wholesale and retail load forecast to be on line in the hour in which prices are being set. Marginal Outage Costs (MOC) - the change in outage costs associated with a change in load, at some specified load level and at a given load increment. For RTP, the increment is usually set at the maximum level of load change that RTP subscribers are likely to undertake in response to RTP prices, although in practice minimum increments required by models used to measure MOC are larger than these increments. Market-Based
Pricing: Electric service prices determined in an open market
system of supply and demand under which the price is set solely by
agreement as to what a buyer will pay and a seller will accept. Such
prices could recover less or more than full costs, depending upon what
the buyer and seller see as their relevant opportunities and risks.
[DOE
Glossary of Electricity Terms] Market Schedule: A schedule of energy to be delivered and/or received at specific points on the transmission system. Market Schedules are not necessarily balanced schedules. They are communicated between Market Participants and Market Operators. Examples from the SMD NOPR include Self-Schedules, Bilateral Transaction Schedules, and schedules from the Day-Ahead and Real-Time Markets for Energy and Ancillary Services. MAS (Multiple Address Radio System): is usually configured as a master radio and multiple slave radios. Masquerade: Masquerade is a security term in which an entity (person or system) pretends to be a different entity and thereby gains the other person's privileges. Masquerade is one of the most common security attacks, in which a hacker learns someone else's password, logs in with that person's privileges, and is therefore free to undertake any number of security attacks such as eavesdropping, modifying data, denying access to data, or using data illegitimately. Master/Slave: Communication management scheme called polling in which one system (the Master) requests one of a group of IEDs (Slaves) to deliver specified information. Only Masters, not Slaves, may issue unsolicited data or commands. Used where data flows primarily between the Slaves and the Master. Quiescent reporting schemes use an implied initial data request solicitation by the Master. Often these terms are used interchangeably with Client/Server, although there are differences: a system may be a Client in one transaction and a Server in another transaction. Masters are always masters; slaves are always slaves. Medium: The material used to support transmission of data. This can be copper wire, coaxial cable, optical fiber, or electromagnetic waves (as in microwaves). Medium Voltage (MV) - Voltage that is higher than 1 kV and lower than 110 kV. This term is used extensively in Europe and other countries, but less frequently in the US. Megabit (Mb, Mbit): 1,000,000 bits; used in describing data transfer rates as a function of time (Mbps). See bit. Megabyte (Mbyte, MB, Meg, or M): 1,048,576 bytes, equal to 1024 kilobytes. Megawatt (MW): One million
watts. [DOE
Glossary of Electricity Terms] Meta: Meta is a prefix that in most information technology usages means "an underlying definition or description." Thus, metadata is a definition or description of data and meta-language is a definition or description of language. Meta derives from Greek, meaning "among, with, after, change." Whereas in some English words the prefix indicates "change" (for example, metamorphosis), in others, including those related to data and information, the prefix carries the meaning of "more comprehensive or fundamental."
Meta-Model: The data that describes data; in other words, a meta-model is a model of data elements that describes what they are, what their name is, how they relate to each other, what transfer format they may use, and other information about the data. Meta-models may be written on paper, or implemented electronically, often using the web technology of XML. See Meta. Meter Data Management Agents (MDMA): An entity, either within a utility or a separate company, that has the mandate to collect, manage, and process metering data for utilities. Metering System - Set of equipment, installations, and programs that facilitate automatic collection and processing of the metering data. MIB (Management Information Base): is a formal description of a set of network objects that can be managed using the Simple Network Management Protocol (SNMP). The format of the MIB is defined as part of the SNMP. (All other MIBs are extensions of this basic management information base.) SNMPv3 provides for defining MIBs using object models, and thus allows new MIBs to be easily defined. Product developers can create and register new MIB extensions. Microsoft Internet Explorer: The web browser Microsoft has produced. It has been installed on all Windows based computers for a year or so. It has become so integrated into the Windows operating system that it is difficult to remove without causing harm to the operating system. Middleware: The concept of middleware comes from the location in a software architecture where it resides. It is between something - in the middle. The something could be a database and a user interface or the messaging between a network and applications, but could also be other parts where an intermediate entity is needed. Hence, the middleware definition is not exact, it has to be used in context with something and depends on who is providing the definition. Another term often used together with middleware is Enterprise Application Integration (EAI). MILNET: One of the DDN networks that make up the Internet; devoted to non-classified military (U.S.) communications. It was built using the same technology as the ARPAnet, and remained in production when the ARPAnet was decommissioned. MIME (Multipurpose Internet Mail Extension): Originally designed for e-mail, as an encoding method for sending non-ASCII files through e-mail servers, MIME has been adopted as a way to also send non-html documents over the World Wide Web. MIME provides a way for non-text information to be encoded as text. This encoding is known as base64. Web servers now must be configured for MIME types to serve those types of files. Most mail clients automatically handle MIME now and the process is transparent to the user. Defined in RFC2045, RFC2046, RFC2047, RFC2048, and RFC2049. A supplement to SMTP. Mirror: Mirrors are exact copies of an original site on the Internet. Mirrors are primarily used for ftp sites although many web sites are also now being mirrored. Mirroring helps distribute traffic among multiple servers so as not to overwhelm the primary. MLM: Multi-Level Marketing MMDS (Multipoint Microwave Distribution System): also know as Multi-channel Multi-point Distribution System and wireless cable, is a wireless broadband technology for Internet Access. MMDS channels come in 6 MHz chunks and runs on licensed and unlicensed channels. Each channel can reach transfer rates as high as 27Mbps (over unlicensed channels: 99MHz, 2.4GHz, and 5.7 to 5.8GHz) or 1Gbps (over licensed channels). MMDS is a line-of-sight service MMF: Make Money Fast MMS: Manufacturing Message Specification Modem (MOdulator-DEModulator): A device used to convert serial digital data from a transmitting terminal to an analog signal suitable for transmission over a telephone channel, or to reconvert the transmitted analog signal to serial digital data for acceptance by a receiving terminal. Modem Speed: The theoretical amount of data that can be transferred. Modem speeds were originally stated in baud rates but that term became outdated with newer technology so now the speeds are referred to in bps or kbps. Because of various conditions, the maximum modem speed is rarely achieved, especially at the higher 33.6kbps and 56kbps speeds. MOF (Meta-Object Facility): is a standardized repository for meta-data; i.e., the descriptions and definitions of the fundamental concepts that applications work with. It is a place to store UML models, but useful for other metadata too - such as the definitions of data types in your data warehouse. See also UML and CORBA. Mosaic: The original web browser, developed at NCSA. It is still the basis for many web browsers today and almost all web browsers still follow the same characteristics that Mosaic established. MPEG (Motion Picture Experts Group): A working group of ISO/IEC in charge of the development of international standards for compression, decompression, processing, and coded representation of moving pictures, audio and their combination. MSMQ (Microsoft Message Queuing): is a messaging system providing guaranteed message delivery, efficient routing, security, and priority-based messaging. It can be used to implement solutions for both asynchronous and synchronous scenarios requiring high performance. MTS (Microsoft Transaction Server): formerly known by its code name, "Viper"—combines the features of a Transaction Processing monitor and an Object Request Broker. It is the transaction service in the Windows NT® operating system. Multicast: Simultaneous transmission of data to a defined group of destinations on a network. Multimedia: The combination of multiple forms of communications including text, graphics, and sound. Multiplex: The division of a single transmission medium into multiple logical channels supporting many simultaneous sessions. Multiprotocol
Label Switching (MPLS): MPLS is a standards-approved
technology for speeding up network traffic flow and making it easier
to manage. MPLS involves setting up a specific path for a given
sequence of packets, identified by a label put in each packet, thus
saving the time needed for a router to look up the address to the next
node to forward the packet to. MPLS is called multiprotocol
because it works with the Internet Protocol (IP),
Asynchronous Transport Mode (ATM),
and
frame relay network protocols. With reference to the standard
model for a network (the Open Systems Interconnection, or
OSI model),
MPLS allows most packets to be forwarded at the
layer 2 (
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IntelliGrid
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