Offset latitude and longitude from a shared midpoint
02Coordinates are angles. One degree contains sixty minutes; one minute contains sixty seconds of arc. LOC stores thousandths of an arcsecond around an unsigned midpoint.
Separate longitude 0.0004 arcseconds west has magnitude 0.4 thousandths of an arcsecond. Rounding away stores one thousandth west:2147483647.
Source for this drawing: RFC 1876 · Read RFC section 2 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
These pictures are analogies to help you learn. The linked RFC explains the actual rules.
Terms in this drawing
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
Latitude 2^31 is the equator; north is greater and south is smaller. Longitude 2^31 is the prime meridian; east is greater and west is smaller.
- Latitude 2^31 is the equator; north is greater and south is smaller. Longitude 2^31 is the prime meridian; east is greater and west is smaller.
- One degree is 3600000 thousandths of an arcsecond. Longitude is rounded away from the prime meridian at the stored resolution.
- These numeric examples describe a center, not a live GPS reading or a guarantee that an entity is there.
Examples are fictional, offline teaching fixtures. RFC1876 is Experimental; its classful IPv4 fallback is historical, not universal current geolocation. Follow the linked official sections for full requirements.
Read the RFC section ↗