INTERNET-DRAFT                                     Vancouver Webpages
draft-daviel-html-geo-tag-00.txt    March 1999 (Expires Sept. 1999)

               Geographic registration of HTML documents

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
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   This memo describes a method of registering HTML documents with a
   specific geographic location through means of embedded META tags. The
   content of the META tags gives the geographic position of the
   resource described by the HTML document in terms of Longitude,
   Latitude and optionally Elevation in a simple, machine-readable
   manner. This information may be used for automated resource discovery
   by means of an HTML indexing agent or search engine.

1.  Introduction

   Many resources described by HTML documents on the World-Wide-Web are
   associated with a particular place on the Earth's surface.  While
   resource discovery on the Web has thus far focussed on document title
   and open-text keyword searching, in these cases it may be beneficial
   to facilitate geographic searching. Examples of this kind of resource
   include pages describing  restaurants, shipwrecks, wildlife refuges

2.  Coordinate Systems

   Resource positions on the Earth's surface should be expressed in
   degrees East of Longitude, degrees North of Latitude as signed
   decimal numbers. The number of decimal places given should reflect
   the precision of the coordinates, with zeroes being used as
   placeholders.  A decimal point is optional where the precision is
   less than one degree. Where the precision of the coordinates is such
   that the datum used is significant, typically more precise than one
   kilometre distance, positions should be converted to the WGS 84 datum
   [3]. Elevations, if given, should be in metres above datum. Positions
   given by a GPS set [4] with datum set to "WGS 84" will in most cases
   be adequate, of the order of 200 metres accuracy.

3.  Implementation

   HTML markup should be added to the document in the form of a META
   statement. This should be placed in the document head in accordance
   with the HTML 4 specification [1].  The identifier "geo.position" is
   used for Longitude, Latitude and optionally Elevation data.  The
   identifier "geo.placename" is used for a free text representation of
   the position, for example "city, province" or "town, county, state".
   The identifier "" is used for the 2-character country code
   from ISO 3166 [5].

   It is anticipated that the "geo.placename" tag be used for resource
   recognition, rather than resource discovery, due to possible
   ambiguities in naming convention, language, word ordering and
   placename duplicates.

   Although the HTML specification [1] states that the name field is in
   general case-sensitive, these "geo" tags should be recognized by
   compliant agents regardless of case.  Coordinates should be ordered
   (Longitude, Latitude [,Elevation]) corresponding to the map
   coordinates (x, y [,z]) as is common cartographic practice.

   4. Examples

     <META NAME="geo.position" content="-123.84,48.54,115">

   describes a resource 115 metres above datum, at position 123.84
   degrees West, 48.54 degrees North, while

     <META NAME="geo.position" content="60,-10">

   describes a resource at position 60 degrees West, 10 degrees South.

     <META NAME="geo.placename" content="London, Ont">
     <META NAME="" content="ca">

   describes a resource in London, Ontario, Canada while

     <META NAME="geo.placename" content="London">
     <META NAME="" content="gb">

   describes a resource in London, England (Great Britain).

5.  Applicability

   As stated in the introduction, certain HTML documents may be
   associated with a geographic position, while other documents are not.
   For proper use of the "geo" tags as described in this draft, the
   resource described in an HTML document should be associated with a
   particular location for the lifetime of the document.  The tags may
   be properly used to describe, for instance, a retail store, a
   mountain peak or a railway station but not an oil company, river,
   aircraft or mathematical theory.

   The geographic position given is associated with the resource
   described by the HTML document, not with the physical location of the
   document [2], or the location of the company responsible for
   publishing or hosting the document. Thus, in some cases the country
   code used in "geo.position" may differ from the country code forming
   part of the host address in the document URL.

6.  Further information

   Further information may be obtained at http://vancouver-webpages/geo/

7.  Security Considerations

   This draft raises no security issues.

8.  References

   [1]  Raggett, Le Hors, Jacobs, "HTML 4.0 Specification",, W3C, April 1998

   [2]  Davis et al., "A Means for Expressing Location Information in
        the Domain Name System", RFC 1876, January 1996
        See also DNS LOC.

   [3]  United States Department of Defense; DoD WGS-1984 - Its
        Definition and Relationships with Local Geodetic Systems;
        Washington, D.C.; 1985; Report AD-A188 815 DMA; 6127; 7-R-
        138-R; CV, KV;

   [4]  ARINC Research Corporation, "Navstar GPS Space Segment /
        Navigation User Interfaces", IRN-200C-002, September 1997
        Related pages: USCG GPS page

   [5]  International Organization For Standardization / Organisation
        Internationale De Normalisation (ISO), "Standard ISO 3166-1988:
        Codes for the Representation of Names of Countries", 1988.
        (e.g. iso3166-countrycodes.txt

9.  Author's Address

   Andrew Daviel
   Vancouver Webpages, Box 357
   185-9040 Blundell Rd
   Richmond BC
   V6Y 1K3

   Tel. (604)-377-4796
   Fax. (604)-270-8285