Civic addresses are represented by the following well-known keys (all of which have string values), which should be kept in sync with those used in XEP-0080 and in the Geoclue project:

• countrycode - s: an ISO-3166-1 alpha-2 (two-letter) country code, e.g. "us", "gb", "fr"
• country - s: a country name in unspecified locale, e.g. "USA"
• region - s: an administrative region of the nation, such as a state or province
• locality - s: a locality within the administrative region, such as a town or city
• area - s: a named area such as a campus or neighborhood
• postalcode - s: a code used for postal delivery
• street - s: a thoroughfare within the locality, or a crossing of two thoroughfares

The following address keys are defined in XEP-0080 but not by Geoclue, and are also allowed:

• building - s: a specific building on a street or in an area
• floor - s: a particular floor in a building
• room - s: a particular room in a building
• text - s: any more specific information, e.g. "Northwest corner of the lobby"
• description - s: A natural-language name for or description of the location, e.g. "Bill's house"
• uri - s: a URI representing the location or pointing to more information about it

Since the previous strings have data intended to be read by users, the language used should be stated using:

• language - s: a specific language or locale of location information in a format compatible to RFC 4646. Note that UTF-8 is the only allowed encoding, e.g. "en" or "fr-CA".

Positions are represented by the following well-known keys:

• lat - d: latitude in decimal degrees north, -90 to +90, relative to the WGS-84 datum

  Rationale:

  This is from XEP-0080; the XEP allows use of a different datum, but recommends this one. We enforce sanity by requiring a consistent datum: a minimal compliant implementation of this specification in terms of XEP-0080 would simply ignore the <lat> and <lon> elements if <datum> exists and has a value other than WGS-84, while an advanced implementation might correct for the different datum.
• lon - d: Longitude in decimal degrees east, -180 to +180, relative to the WGS-84 datum

  Rationale:

  Same rationale as 'lat'
• alt - d: altitude in metres above sea level (negative if below sea level)

  Rationale:

  This is from XEP-0080
• accuracy - d: horizontal position error in metres if known

  Rationale:

  This is from XEP-0080

Velocities are represented by the following well-known keys:

• speed - d: speed in metres per second

  Rationale:

  This is from XEP-0080
• bearing - d: direction of movement in decimal degrees, where North is 0 and East is 90

  Rationale:

  This is from XEP-0080, and is equivalent to the struct field called "direction" in GeoClue

Other well-known keys:

• timestamp - x (Unix_Timestamp64): the time that the contact was at this location, in seconds since 1970-01-01T00:00:00Z (i.e. the beginning of 1970 in UTC)

  Rationale:

  XEP-0080 uses an ISO 8601 string for this, but a number of seconds since the epoch is probably easier to work with.