Here you go:
1)
MEA: The lowest published altitude (or Flight Level) between radio fixes that meets obstacle clearance requirements between those fixes and in many countries assures acceptable navigational and radio signal coverage.
2)
MORA: A route MORA provides a reference point clearance within 10 NM (18.5 km) of the route centreline (regardless of the route width) and end fixes.
A grid MORA altitude provides a reference point clearance within the section
outlined by latitude and longitude lines.
MORA values clear all reference points by 1000 ft (300 m) in areas where the
highest reference points are 5000 ft (1500 m) MSL, or lower. MORA values clear all reference points by 2000 ft (600 m) in areas where the reference points are above 5000 ft (1500 m) MSL. When a MORA is shown along a route as "unknown" or within a grid as "unsurveyed" a MORA is not shown due to incomplete or insufficient information.
For interest, these are also relevant:
3)
MOCA: (Minimum Obstacle Clearance Altitude) The lowest published altitude in effect between radio fixes on VOR airways, offairways routes, or route segments, which meets obstacle clearance requirements for the entire route segment.
4)
MSA: (Minimum Sector Altitude) Altitude depicted on instrument approach, SID or STAR charts and identified as the minimum safe altitude which provides a 1000 ft (300 m) obstacle clearance within a 25 NM (46 km) (or other value as stated) radius from the navigational facility upon which the MSA is predicated.
Hope this helps!
LOC
