The geo URI scheme is a Uniform Resource Identifier (URI) scheme defined by the Internet Engineering Task Force's RFC 5870 (published 8 June 2010) as:
a Uniform Resource Identifier (URI) for geographic locations using the 'geo' scheme name. A 'geo' URI identifies a physical location in a two- or three-dimensional coordinate reference system in a compact, simple, human-readable, and -independent way.
The current revision of the vCard specification supports geo URIs in a vCard's "GEO" property, and the GeoSMS standard uses geo URIs for geotagging SMS messages. Android based devices support geo URIs, although that implementation is based on a draft revision of the specification, and supports a different set of URI parameters and query strings.
A geo URI is not to be confused with the site GeoUrl (which implements ICBM address).
A simple geo URI might look like:
where the two numerical values represent latitude and longitude respectively, and are separated by a comma. If a third comma-separated value is present, it represents altitude. Coordinates in the Southern and Western hemispheres as well as altitudes below the coordinate reference system (depths) are signed negative with a leading dash. The geo URI also allows for an optional "uncertainty" value, separated by a semicolon, representing the uncertainty of the location in meters, and is described using the "u" URI parameter. A geo URI with an uncertainty parameter looks as follows:
A geo URI may, for example, be included on a web page, as HTML:
so that a geo URI-aware user agent such as a web browser could launch the user's chosen mapping service; or it could be used in an Atom feed or other XML file.
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