[tei-council] Further update on PH

Syd Bauman Syd_Bauman at Brown.edu
Tue Sep 25 13:37:47 EDT 2007


> Maybe "numbers" is a bit vague, but the experts we consulted was
> pretty clear that the content of geo should be just that -- two
> sequences of decimal digits, no units, no fancy notation. Thats
> what every GIS system I've looked at uses too, so makes sense to
> me. Think KML.

Great! I think that's fine. But let's explicitly say so (and enforce
it), then.

---------
<?xml version="1.0" encoding="utf-8"?>
<!--Copyright TEI Consortium.
Licensed under the GNU General Public License.
See the file COPYING for details
$Date:$

$Id:$
-->
<elementSpec xmlns="http://www.tei-c.org/ns/1.0"
             xmlns:rng="http://relaxng.org/ns/structure/1.0"
             module="namesdates" usage="opt" ident="geo">
  <gloss>geographical coordinates</gloss>
  <desc>contains an expression of a set of geographic coordinates,
  representing a point, line, or area on the surface of the earth as a
  sequence of one or expressions of latitude and longitude.</desc>
  <classes>
    <memberOf key="model.measureLike"/>
  </classes>
  <content>
    <rng:list>
      <rng:oneOrMore>
        <rng:data type="decimal">
          <rng:param name="minInclusive">-90</rng:param>
          <rng:param name="maxInclusive">90</rng:param>
        </rng:data>
        <rng:data type="decimal">
          <rng:param name="minInclusive">-180</rng:param>
          <rng:param name="maxInclusive">180</rng:param>
        </rng:data>
      </rng:oneOrMore>
    </rng:list>
  </content>
  <exemplum>
    <egXML xmlns="http://www.tei-c.org/ns/Examples">
      <!-- a point in Providence, USA -->
      <geo>41.8280 -71.4009</geo>
      <!-- a line between there and Oxford, UK -->
      <geo>41.8280 -71.4009 51.7594 1.2604</geo>
    </egXML>
  </exemplum>
  <remarks>
    <p>All uses of <gi>geo</gi> within a document, or within a
    particular declared element (i.e., one that is a member of <name
    type="class">att.declaring</name>) if two or more <gi>geoDecl</gi>
    elements is present in the TEI Header, are required to use the
    same coordinate system, which is that defined by a
    <gi>geoDecl</gi> element supplied in the TEI Header. If no such
    element is supplied, the assumption is that the content of each
    <gi>geo</gi> element will be a pair of numbers to be interpreted
    as latitude followed by longitude according to the World Geodetic
    System.</p>
    <p>Latitude should be expressed as a decimal number of degrees
    from the equator, ranging from -90 to 90, with locations south of
    the equator indicated with a negative number; those north of the
    equator may have an optional plus sign. Longitude should be
    expressed as a decimal number of degrees from the prime meridian,
    ranging from -180 to 180, with locations west of the prime
    meridian indicated with a negative number; those east of the prime
    meridian may have an optional plus sign.</p>
  </remarks>
</elementSpec>
---------

Note that we should check with the experts to see if 90 and 180 are
the actual maximum absolute values. It may be the case that a bit of
fudge factor is needed if you want to express, say, OSGB 36 values
converted to WGS84. Idunno. 

The declarable stuff is a compromise: already quite verbose, but
actually does not describe that we're only talking about the nearest
ancestor declarable element.



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