What does the AEX in ESRI basemap source stand for?

[KabindraAdhikari]

Credits (Attribution)

Source: ESRI, i-cubed, USDA FSA, USGS, AEX, GeoEye, AeroGRID, Getmapping, IGP

[curtvprice]

My guess would be Aerials Express. 

See: Contributors for the World Imagery Map for details on the base map.

This page was linked from the main AGOL content page for the World Imagery map layer:

https://www.arcgis.com/home/item.html?id=10df2279f9684e4a9f6a7f08febac2a9