Table 5.16 -- EDCS Classifications whose label begins with M
| Label | Definition | Related concepts | Code |
| MAGNETIC_DEVICE | Equipment used for the collection of magnetic data. | 471 | |
| MAGNETIC_DISTURBANCE | A localized anomaly in a planetary magnetic field. | 472 | |
| MAGNETIC_POLE | Either of the two places on the planetary surface where, given the presence of a planetary magnetic field, the magnetic dip is 90 arc degrees, i.e., locally vertical. | 473 | |
| MAGNETIC_STATION | The location of a magnetic data collection device. | 474 | |
| MAGNETOSPHERE | The region of space where the planetary magnetic field balances the pressure of the solar wind. | 475 | |
| MAGNETOSPHERE_PLASMA | The flux of charged particles within the planetary magnetosphere. | 476 | |
| MAIN_TELECOM_EXCHANGE | A structure housing a central system of switches and other equipment that establishes connections between individual telecommunication devices, e.g., telephones. | EC TELECOM_SWITCHING_STATION | 477 |
| MAN_MADE_AIR_OBSTRUCTION | A man-made structure of sufficient height to impede or obstruct flight operations and cause a hazard to air navigation. | 478 | |
| MAN_MADE_CLEARING | A man-made clearing in a cultural region or passing through a stand of trees, designed to: provide access for a road, railroad, pipeline, or power transmission line; demarcate a boundary; obtain survey line-of-sight; or impede the progress of forest fires. | EC FIREBREAK, EC GLADE, EC LAND_EASEMENT | 479 |
| MAN_MADE_OBJECT | An object made by human beings, e.g., a bridge, building, dam, road or runway. | 480 | |
| MANUFACTURING_FACILITY | A site and associated buildings devoted to the manufacture of goods. | EC FACTORY | 481 |
| MAP_BOUNDARY | A boundary that encloses all water, streets, parcels, and buildings. | 482 | |
| MAP_LEGEND_INFORMATION | Auxiliary information about a map. | 483 | |
| MAP_SHEET_FRAME | A drawing frame for a map; may include associated parameters. | 484 | |
| MARINE_BAY | A body of water partially enclosed by land but with a wide mouth, affording access to the sea, e.g., a bay. | EC SEA | 485 |
| MARINE_CHANNEL | A broad strait, especially one that connects two seas. | EC SEA | 486 |
| MARINE_SOUND | A long, relatively wide body of water, larger than a strait or a channel, connecting larger bodies of water, e.g., seas or oceans. | EC MARINE_CHANNEL, EC OCEAN, EC SEA, EC STRAIT | 487 |
| MARITIME | Of, relating to, or characteristic of ships, shipping, sailors, or navigation on a body of water (nautical), e.g., a port, harbour, navigation aid, or maritime dangers/hazards. | 488 | |
| MARITIME_FOUL_GROUND | A region of comparatively shallow water strewn with rocks, boulders, coral, wreckage, or other obstructions, making it unsuitable for anchoring, grounding, or ground fishing. | 489 | |
| MARITIME_LIMIT_BOUNDARY | A line where on either side certain activities or factors of significance to navigation and/or operation apply. | 490 | |
| MARITIME_MOLE | A loading and discharge place for vessels; it is usually a substantial masonry structure, and often serves as a breakwater on its outer side while offering facilities for ships in its inner side. | EC BREAKWATER, EC GROIN, EC JETTY | 491 |
| MARITIME_NAVAID | A NAVAID intended to support maritime operations, e.g., a beacon or buoy. | 492 | |
| MARITIME_PETROLEUM_FIELD | A maritime region where petroleum (e.g., oil or natural gas) is pumped or otherwise removed from the ground. | EC PETROLEUM_FIELD | 493 |
| MARITIME_PLATFORM | A flat surface raised above the sea, as a working stage for conducting offshore operations. | 494 | |
| MARITIME_POLICE_STATION | A building that serves a governmental department established to maintain order, enforce the law, and prevent and detect crime in a harbour or coastal region. | EC POLICE_STATION | 495 |
| MARITIME_RAMP | A partially submerged hard surfaced construction on a shoreline for launching and retrieving vessels or vehicles. | EC RAMP | 496 |
| MARITIME_REGION | A maritime region in which certain activities or factors of significance to navigation and/or operation apply. | 497 | |
| MARITIME_ROUTE | A track or lane established for the safe passage of ships. | EC DEEP_WATER_ROUTE | 498 |
| MARITIME_ROUTE_CN | An abstract description of the connectivity (centerline or nexus) afforded by a maritime route. | EC MARITIME_ROUTE | 499 |
| MARITIME_SIGNAL_STATION | A station on shore from which signals are made to ships at sea. | 500 | |
| MARITIME_WRECK | The ruined remains of a vessel. | 501 | |
| MARKET | An open space or building where goods are offered for sale. | EC COMMERCIAL_BUILDING, EC MARKETPLACE, EC RETAIL_FACILITY, EC SHOPPING_CENTRE, EC TRADING_POST | 502 |
| MARKETPLACE | An open space or building where goods are offered for sale by several vendors. | EC MARKET | 503 |
| MARSH | A tract of soft, wet, low-lying land, characterized by grassy vegetation and often forming a transition zone between water and land. | EC BOG, EC SWAMP | 504 |
| MARSH_OR_SWAMP | A saturated tract of land, at times covered with water, supporting vegetation that may include trees. May be further delineated specifically as EC MARSH or EC SWAMP. | EC LAND_FLOODS_PERIODICALLY | 505 |
| MARTELLO_TOWER | A stone tower serving the purpose of coastal or harbour defence, usually including a gun platform, ammunition magazine and accommodations for a garrison, e.g., a Martello tower. | 506 | |
| MAST | A straight piece of timber or a hollow cylinder of wood or metal set up vertically, or nearly so. | EC FLAGPOLE | 507 |
| MATERIAL_CHARSET | A set of physical characteristics of the material composing an object, e.g., density. | 508 | |
| MEASURED_DISTANCE_LINE | A course whose length has been accurately measured and is used in conjunction with ranges ashore by vessels to calibrate logs, engine revolution counters, other onboard equipment, and to determine speed. | 509 | |
| MEDICAL_CENTRE | A site containing one or more buildings devoted to medical research or the practice of medicine. | EC HEALTH_OFFICE, EC SANITARIUM | 510 |
| MESH_FACE_CHARSET | A set of characteristics describing the faces of a related mesh. | 511 | |
| MESH_FACE_SET | A set of faces comprising a mesh, each face defined in terms of the vertices (three or more) joining its bounding edges. | 512 | |
| MESH_SOLID_CHARSET | A set of characteristics describing the solid elements of a related mesh. | 513 | |
| MESH_SOLID_SET | A set of solid elements comprising a mesh, each solid element defined in terms of its bounding faces (four or more). | 514 | |
| MESH_VERTEX_CHARSET | A set of characteristics describing the vertices of a related mesh. | 515 | |
| MILITARY_BATTERY | An emplacement for one or more pieces of artillery. | 516 | |
| MILITARY_INSTALLATION | A site or tract of land, protected by fortifications or natural advantages, from which military operations proceed, e.g., forward movements are made, or supplies are furnished. | 517 | |
| MILITARY_OPERATIONS_BLDG | A building devoted to the act or process of managing military forces or overseeing the conduct of military operations. | 518 | |
| MILITARY_PERSONNEL | Humans who are members of an armed force. | EC CIVILIAN_PERSONNEL, EC NON_HUMAN_ANIMAL | 519 |
| MILITARY_SITE | A site containing a concentration of military buildings or related structures. | 520 | |
| MILITARY_TRENCH | A linear excavation dug for military purposes. | EC ENGINEER_DITCH | 521 |
| MINEFIELD | A region of land or water throughout which explosive mines have been laid. | 522 | |
| MINERAL_PILE | A man-made heap of mining or quarrying products excluding waste materials. | EC DISPOSAL_SITE | 523 |
| MISC_HYDROLOGY_OBJECT | A hydrological object which is of a minor nature and which is not included in a more specific characterization. | 524 | |
| MISC_OBSTACLE | An obstacle which is of a minor nature and which is not included in a more specific characterization. | 525 | |
| MISSILE_SITE | A site with related facilities for storing and launching missiles. | 526 | |
| MISSION | A building that houses persons sent to a foreign land by a religious organization, especially a Christian organization, to spread its faith or provide educational, medical, and other assistance. | 527 | |
| MIXED_URBAN_REGION | A region containing buildings or other structures in combination with undeveloped or agricultural tracts of land. | EC BUILT_UP_REGION, EC TOWN | 528 |
| MIXED_VEGETATION_LAND | A tract of land covered by a mixture of woody and non-woody vegetation types. | 529 | |
| MOAT | A trench, usually filled with water, that surrounds a tract of land. | 530 | |
| MOBILE_HOME | A trailer used as a dwelling, and designed to be easily moved from site to site. | EC MOBILE_HOME_PARK | 531 |
| MOBILE_HOME_PARK | A site for the permanent parking of trailers used as dwellings and designed without a permanent foundation. | EC CAMPGROUND, EC MOBILE_HOME, EC VEHICLE_LOT | 532 |
| MONUMENT | A structure erected or maintained as a memorial to a person or event. | EC CAIRN, EC GRAVE_MARKER | 533 |
| MOORING_DOLPHIN | A post or group of posts used for mooring, warping a ship or as an aid to navigation. | 534 | |
| MOORING_FACILITY | A region and structures used for mooring/warping a ship. | 535 | |
| MOORING_MAST | A tower-like structure used to secure an airship. | 536 | |
| MOORING_RING | A metal ring attached to a structure and used to secure a vessel. | 537 | |
| MOORING_TROT | A complex object consisting of an anchor plus a related floating navigational mark. | EC ANCHOR, EC NAVIGATIONAL_MARK_AFLOAT | 538 |
| MORAINE | An accumulation of soil and stone debris deposited by a glacier. | EC GLACIER | 539 |
| MORTAR | A muzzle loading cannon for firing shells at low velocities, short ranges and high trajectories. | 540 | |
| MOTEL | A building used to provide lodging for motorists in rooms usually having direct access to an open parking lot, e.g., a motel, motor court or motor lodge. | EC HOTEL | 541 |
| MOUNTAIN_PASS | A natural route through a low place in a mountain range. | EC MOUNTAINOUS_REGION | 542 |
| MOUNTAINOUS_REGION | A region whose physiography consists predominantly of mountains. | EC VALLEY_REGION | 543 |
| MUD_LINE | A boundary of an expanse of mud that covers and uncovers, depending on the elevation of the terrain surface above the vertical datum and the current elevation of the water surface. | EC LOW_WATER_LINE, EC SAND_LINE | 544 |
| MULTI_UNIT_DWELLING | A building providing residence for multiple sets of occupants. | EC APARTMENT_HOUSE, EC ROWHOUSE | 545 |
| MULTIDOMAIN_VEHICLE | A vehicle capable of operation in more than one environmental domain (e.g., air, land, ocean surface, submersible, or space), excluding those assignable to another vehicle classification. | 546 | |
| MUNICIPAL_HALL | A building that contains the offices of the public officials of a local political unit. | EC CITY_HALL | 547 |
| MUNICIPAL_UTILITY_FACILITY | A site and associated structures devoted to the provision of services to the residents of a locally governed region; e.g., electricity, telecommunications, gas, water, sewage, or trash collection/disposal. | 548 | |
| MUNITION | A complete device charged with explosives, propellants, pyrotechnics, initiating composition, or nuclear, chemical, or biological material for use in military operations, including demolitions. | 549 | |
| MUSEUM_BUILDING | A building devoted to the acquisition, conservation, study, exhibition, and educational interpretation of objects having scientific, historical, or artistic value. | 550 | |
| MUSEUM_COMPLEX | A site and associated buildings devoted to the acquisition, conservation, study, exhibition, storage, and educational interpretation of objects having scientific, historical, or artistic value. | 551 |