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RFC 5870 / START HERE

geo location links, before the details

geo location links. “geo” is a scheme name referring to geography, not an acronym. URI means Uniform Resource Identifier.

A geo URI identifies a physical location using latitude and longitude, with optional altitude and uncertainty. Its default coordinate reference system is WGS-84: the rules that give those numbers geographic meaning.

Start the guide See the 5 chapters ↓

The idea in one picture

  1. Location URI

  2. Read coordinates

  3. Optional map use

A simplified picture of the idea; the chapters explain the actual mechanisms.

Why it exists

RFC 5870 provides a short location identifier independent of a particular map company or network protocol. It specifies coordinate syntax, interpretation, comparison and privacy boundaries, rather than an HTTP map service, a street-address format or continuous location tracking.

A familiar example

A public landmark link such as geo:13.4125,103.8667 can be handed to a supporting map application. The URI identifies the coordinates; it does not guarantee an installed handler, prove someone is there or give permission to disclose a person’s location. You will learn why missing altitude differs from zero and why extra digits do not prove accuracy.

Helpful background

You can start here without reading another RFC. If these ideas are unfamiliar, these short introductions may help.

URI syntaxRFC 3986 · beginner overview ↗

What you’ll learn next

Begin with chapter one, or choose a topic.

  1. From a link to coordinatesA geo URI identifies a physical location. A supporting application extracts coordinates; it chooses what to do with them.
  2. Missing altitude is not zeroA missing height, an explicit zero and a positive height convey different information.
  3. Uncertainty changes the locationThe optional u parameter explicitly carries uncertainty in meters across all given dimensions.
  4. Compare meaning, not spellingEquivalent geo URIs can have different numeric spellings. Unknown extension values require caution.
  5. Validate before using or sharingA parser can read a string that still fails geographic or reference-system checks. Sharing it can reveal a person’s location in context.
Start with chapter one →

This introduction explains RFC 5870 (2010). Read the original RFC ↗