How to define Space Oblique Mercator projection in EML?...

[Mark Servilla]

EML wizards and gurus,

I am having trouble defining the Space Oblique Mercator map projection
in the spatialRaster subtree of EML.  The problem is unique to the SOM
(any oblique map projection, for that matter) projection - the SOM does
not use a prime meridian in the usual sense (i.e., it is fixed to the
flight path of the Landsat satellite, not a geographic coordinate system).
Since EML requires the primeMeridian-longitude and unit-name attributes
to be strictly defined, the document will not validate.  Is there a
recommendation *thanks in advance* from the EML community for how to deal
with this issue, perhaps making the aforementioned attributes optional?

I have included below an example of how I would define this projection.

Notes:
1. The SOM projection does not appear to be common in the remote
sensing world other than EOSAT/Landsat/IRS formats.  Unfortunately, we have
much data in this projection.
2. FGDC has a separate element for this projection in their schema.
Actually, FGDC has a separate element for each major projection definition.

<spatialReference>
     <horizCoordSysDef name="SOM">
         <projCoordSys>
             <geogCoordSys>
                 <datum/>
                 <spheroid name="International_1909" semiAxisMajor="6378388"  denomFlatRatio="0.996633"/>
                 <primeMeridian longitude=""/>
                 <unit name="">
             </geogCoordSys>
             <projection>
                 <parameter name="Landsat_Number" value="5"/>
                 <parameter name="Landsat_Path" value="36"/>
                 <parameter name="False_Easting" value="0"/>
                 <parameter name="False_Northing" value="0"/>
                 <unit name="meter">
             </projection>
         </projCoordSys>
     </horizCoordSysDef>
</spatialReference>

Sincerely,
Mark
-- 
Mark Servilla, Ph.D.

LTER Network Office
Department of Biology
MSC 03 2020
1 University of New Mexico
Albuquerque, NM 87131-0001

servilla at lternet.edu
Office (505) 277-2619
Cell   (505) 453-8593