STC Version 1.20

[Arnold Rots]

I just submitted STC version 1.20 to the IVOA repository.
It includes updates to the Working Draft, the STC-XML document, the
three schema files, and a new document: Linear STC.
It can be previewed through the NVO project page:

	http://us-vo.org/projects/project.cfm?ID=62

Note that the versions of the schemata on my private web page have a
schemaLocation, whereas the ones submitted to the IVOA site do not.

Most of the changes will not be very noticeable and fall in the categories:

- Changes to force schema validation by Xerces-J2;
  this has resulted in some obfuscation of the schema but does not
  really affect any instances (I think)
- SpaceFrames updates and clarifications; this mainly affects
  planetary systems
- Time: added timescale TEB (Barycentric Ephemeris Time), restricted
  the use of ISOTime to > 0001-01-01 (since someone had the audacity to
  put a minus sign in front)
- Brought units in compliance with FITS standard
- Require Polygons to have sides < 180 deg, consistent with AST rules
- Added Box shape
- Revised the definition of position angle

I append the list of changes from version 1.10

Linear STC is a "command line" implementation of STC, with an eye
toward ADQL and human readability; read the first three pages of the
document if you are interested.

Enjoy,

  - Arnold

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Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
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Appendix D  -  Changes from Previous Versions

>From V1.10 to V1.20:

    * Distinguished LSRK and LSRD; replaced SUPER_GALACTIC_CENTER by
LOCAL_GROUP_CENTER 
    * Added Box shape to Region
    * Require polygon sides to be less than 180°; added explanation on
defining inside and outside 
    * Added LinearSTC implementation
    * Subtle changes to the schemata to force validation under
Xerces-J2; this did not change anything but made the schemata a little
uglier 
    * Changed units "micron" and "A" to "um" and "Angstrom",
respectively, consistent with the FITS standard 
    * Added timescale TEB, with references
    * Added warning on use of ISOTime and restricted its use explicitly
    * Added an explicit definition of Position Angle; in the XML
implementation it is now an element, rather than an attribute (see,
e.g., Ellipse) 
    * Added a reference spheroid to GEO_D, changed GEO to GEO_C
    * Added an explicit discussion of planetographic and
planetocentric coordinate systems, with references, as well as a
discussion of right-handed and left-handed systems 
    * Removed GEOGRAPHIC CoordFlavor, replacing it by 3-dimensional
SPHERICAL, and added POLAR