- Material Consideration - Any issue which relates to the use and development of land and is relevant to the planning process.
- Metropolitan Development Limit - A continuous development limit around the Contiguous Development Zone and comprising development limits for Metropolitan:-
- North Down and
- Belfast City
- Metropolitan Rural Area - Defined for purposes of allocating the 9,000 dwellings, which form part of the total Housing Growth Indicator to the BMA and hinterland in the RDS, as those areas lying within The Belfast Metropolitan Area but outside The Metropolitan Urban Area.
- Metropolitan Urban Area - Defined for purposes of allocating the 42,000 dwellings, which form part of the total Housing Growth Indicator to the BMA in the RDS, as the Contiguous Development Zone and the City of Lisburn and towns of Bangor, Carrickfergus and Holywood.
- MHz/GHz - A measurement of frequency in the ultra high frequency band from 300MHz (MegaHertz) to 3GHz(GigaHertz). PCN and Cellular operators use different parts of this spectrum (at 1.8 GHz and 900MHz respectively).
- MSC or MTX - Mobile Switching Centre or Mobile Telephone Exchange. A centralised switching centre through which calls in a given geographical area will be routed. Full integration with the PSTN allows mobile to fixed national and international calls as well as mobile to mobile.
- Municipal waste - Household waste and any other waste under the control of district Councils or their agents acting on their behalf.