MAPEMs describe the topology of an intersection (ETSI TS 103 301): the geometry of its lanes, which ingress and egress lanes exist, and which maneuvers connect them.

A MAPEM contains, among other things:

1. the reference position of the intersection
2. lane geometries (as offset points)
3. lane attributes (vehicle lane, bike lane, crosswalk, …)
4. the allowed connections between lanes, referenced by signal groups

MAPEMs are sent by C-ITS traffic lights (RSUs). On their own they are mostly static — the dynamic signal states are transmitted separately via SPATEM; both together enable use cases such as GLOSA (Green Light Optimal Speed Advisory).