Geo Uri Information
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 protocol-independent way.[1]
The current revision of the vCard specification[2] supports 'geo' URIs in a vCard's "GEO" property, and the GeoSMS standard uses 'geo' URIs for geotagging SMS messages.
A 'geo' URI is not to be confused with the site GeoUrl[3] (which implements ICBM address).
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Example
A simple 'geo' URI might look like:
geo:37.786971,-122.399677
where the two numerical values represent latitude and longitude respectively,[1] and are separated by a comma.[1] If a third comma-separated value is present, it represents altitude.[1] 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.[1] A 'geo' URI with an uncertainty parameter looks as follows:
geo:37.786971,-122.399677;u=35
A 'geo' URI may, for example, be included on a web page, as HTML:
<a href="/geo:37.786971,-122.399677;u=35">Wikimedia Headquarters</a>
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.
Coordinate reference systems
The default coordinate reference system (CRS) used is the World Geodetic System 1984 (WGS-84),[1] for planet Earth although other CRS, once defined, may be specified, using the "crs" URI parameter,[4] also separated by a semicolon. Such CRSs may include both other terrestrial systems and those for non-terrestrial coordinates such as those on the Moon or Mars.
A 'geo' URI for a hypothetical lunar CRS created in 2011 might be:
geo:37.786971,-122.399677;u=35;crs=Moon-2011
The order in which the semicolon-separated parameters occur is not significant,[1] and 'crs' parameter values are case-insensitive,[1] so the above example is exactly equivalent to:
geo:37.786971,-122.399677;crs=moon-2011;u=35
References
- ^ a b c d e f g h i "RFC 5870 - A Uniform Resource Identifier for Geographic Locations ('geo' URI)". Internet Engineering Task Force. 2010-06-08. http://tools.ietf.org/html/rfc5870. Retrieved 9 June 2010.
- ^ "draft-ietf-vcarddav-vcardrev-11 - vCard Format Specification, section-6.5.2". IETF. http://tools.ietf.org/html/draft-ietf-vcarddav-vcardrev-11#section-6.5.2. Retrieved 10 June 2010.
- ^ Geourl.org
- ^ RFC 5870, section 8.3
External links
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Categories: Internet protocols | Web development | Geocodes | Geographic information systems | URI schemes |
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