SharedGeo proudly serves as custodian of the nation's largest and most authoritative collection of information about the non-proprietary federal cartographic and emergency/disaster response geolocation standard, United States National Grid (USNG).  The prominent numbers and letters on an ELM are the U.S. National Grid (USNG) coordinates of the marked location. 

To learn more about the USNG, click the link below.

United States National Grid Information Center