M&C: Maintenance and Construction
MaaS: Mobility-as-a-Service
MAC: Medium Access Control
MAP: Map Data Message
MAP-21: Moving Ahead for Progress in the 21st Century Act
MAPSS: Mobile Accessible Pedestrian Signal System
MARAD: Maritime Administration
Mbps: Megabits per second
MCM: Maintenance and Construction Management
MCMC: Maintenance and Construction Center
MCMS: Maintenance and Construction Subsystem (legacy National ITS Architecture)
MCO: Maintenance and Construction Operations
MCV: Maintenance and Construction Vehicle
MCVS: Maintenance and Construction Vehicle Subsystem (legacy National ITS Architecture)
MDSS: Maintenance Decision Support System
M-ISIG: Multi-Modal Intelligent Traffic Signal System
MMITSS: Multi-Modal Intelligent Traffic Signal Systems
MMRTTI: Multimodal Real-Time Traveler Information
MOD: Mobility on Demand
MOU: Memorandum of Understanding
MP: Market Package (legacy National ITS Architecture)
MPA: Metropolitan Planning Area
MPG: Miles per Gallon
MPH: Miles per Hour
MPO: Metropolitan Planning Organization
MS/ETMCC: Message Set for External TMC Communication
MTP: Metropolitan Transportation Plan
MUTCD: Manual on Uniform Traffic Control Devices