[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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