draft-daviel-html-geo-tag-03







INTERNET-DRAFT                                     Vancouver Webpages
<draft-daviel-html-geo-tag-03.txt>    Sept 2000 (Expires Mar. 2001)

               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.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   Drafts.

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   The list of Internet-Draft Shadow Directories can be accessed at
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Abstract

   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
   etc.




A.Daviel                                                        [Page 1]

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2.  Coordinate Systems

   Resource positions on the Earth's surface should be expressed in
   degrees North of Latitude, degrees East of Longitude as signed
   decimal numbers.  Elevation should be expressed as a signed decimal
   number of metres above datum. 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 15 metres
   accuracy (with SA off).


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  Latitude, Longitude 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 "geo.region" is used for the country subdivision code
   from ISO 3166-2 [10].

   For resources within the United States and Canada, the "geo.region"
   identifier as given by ISO 3166-2 is typically constructed from the
   2-character country code [5] as used in Internet domain names, and
   the common 2-character State/Province codes [8][9], joined with a
   hyphen, for example "CA-BC" for British Columbia, Canada.

   Where the official subdivision code is unknown, the 2-character
   country code alone may be used in "geo.region", for example "DE" for
   Germany.

   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
   (Latitude ; Longitude) as for RFC 2426, RFC 2445 (vCard and iCal
   specifications) [6][7].  If elevation is given, coordinates should be



A.Daviel                                                        [Page 2]

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   ordered (Latitude ; Longitude ; Elevation).  (This is at variance
   with common GIS practice, but better matches the intended audience of
   this Draft.)

   The Metadata Profile "http://geotags.com/geo" may be used as defined
   in [1] to define the geo tag properties.

   4. Examples

     <HEAD profile="http://geotags.com/geo">
     <META name="geo.position" content="48.54;-123.84;115">

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

     <META name="geo.position" content="-10;60">

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

     <META name="geo.placename" content="London, Ont">
     <META name="geo.region" content="CA-ON">

   describes a resource in London, Ontario, Canada, while

     <META name="geo.placename" content="London">
     <META name="geo.region" content="GB">

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

   The HTML attributes "lang", "dir" may be used to define the language
   and directionality for the "geo.placename" tag as defined in [1], for
   instance

     <META name="geo.placename" lang="fr" content="Londres">


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 a multinational company,
   river, aircraft or mathematical theory.

   The geographic position given is associated with the resource



A.Daviel                                                        [Page 3]

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   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://geotags.com/geo

7.  Security Considerations

   This draft raises no security issues.

8.  Internationalization considerations

   The "geo.placename" tag content is free text, and should obey the
   internationalization rules of HTML 4. "lang" and "dir" modifiers may
   be used to specify the language of the content. Multiple instances of
   geo.placename may be used with different "lang" modifiers.
   Geo.placename content is coded using the character set of the
   containing document.

   Geo.position and geo.region tag content should use US-ASCII or UTF-8.

9.  References

   [1]  Raggett, Le Hors, Jacobs, "HTML 4.0 Specification",
        http://www.w3.org/TR/1998/REC-html40-19980424 , W3C, April 1998

   [2]  Davis et al., "A Means for Expressing Location Information in
        the Domain Name System", RFC 1876, January 1996
        http://www.alternic.org/rfcs/rfc1800/rfc1876.txt

   [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

   [5]  International Organization For Standardization / Organisation
        Internationale De Normalisation (ISO), "Standard ISO
        3166-1:1997: Codes for the Representation of Names of
        Countries and their subdivisions -- Part 1: Country codes",
        1997.




A.Daviel                                                        [Page 4]

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   [6]  Dawson & Stenerson, Internet Calendaring and Scheduling Core
        Object Specification (iCalendar), RFC 2445, November 1998
        http://www.alternic.org/rfcs/rfc2400/rfc2445.txt

   [7]  Dawson & Howes, vCard MIME Directory Profile, RFC 2426,
        September 1998
        http://www.alternic.org/rfcs/rfc2400/rfc2426.txt

   [8]  United States Postal Service, Official Abbreviations -
        States and Possessions,
        http://www.usps.gov/ncsc/lookups/abbr_state.txt

   [9]  Canada Post, the Postal Code, two-letter abbreviations,
        http://www.canadapost.ca/CPC2/addrm/addrguide/prov_symbols.html


   [10] International Organization For Standardization / Organisation
        Internationale De Normalisation (ISO), "Standard ISO
        3166-2:1998: Codes for the Representation of Names of Countries
        and their subdivisions -- Part 2: Country subdivision code",
   1998.

10.  Author's Address

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

   Tel. (604)-377-4796
   Fax. (604)-270-8285
   andrew@vancouver-webpages.com

















A.Daviel                                                        [Page 5]