updated SSA schema for the registry

[Doug Tody]

Hi Ray -

> The IVOA twiki page, SsaResourceSchema, has the latest SSA extension
> schema posted as SSA-wd.xsl.  If there are no further comments on this,
> we will release it as an external working draft and begin using it
> in our registries.
> 
> On advice of the SSA spec editor, this latest version distinguishes
> pre-1.0 implemenatations from truely v1.0 compliant is with different
> capability xsi:types: "SimpleSpectralAcces" for post 1.0 versions
> and "ProtoSpectralAccess."  Please review the section labeled,
> "Representing v1.0 and pre-1.0 Implementations".
> 
> LAST CHANCE FOR COMMENTS!
> 
> thanks!
> Ray

I uploaded a new version of the SSA resource schema to the above TWiki
page.  I did not change anything else on the page since I imagine you
would like to confirm the changes before accepting anything of this.

While there were quite a few edits (see below) they are mostly minor
and I doubt if they will affect the ongoning registry implementations.
The semantics and document notes though will be important when it comes
time for SSA implementors to actually fill in this metadata.

You guys have moved along greatly with this in trying to get
getCapabilities defined for SSA V1.1!  About all that is left at this
point, is adding a set of optional capabilities (the "supports" element),
and tweaking how the service parameters are defined.

	- Doug


----- summary of changes from V0.3 ----

     -   o  In maxSearchRadius, noted that this differs from SIZE which
            specifies the diameter of the search region.
	 o  In maxRecords, noted that if not specified there is no
	    predefined hard limit on the size of a query response.
	 o  In defaultMaxRecords, noted that if not specified the default
	    maxRecords is undefined (but there might nonetheless be one).
	 o  In maxAperture added mention that the units are diameter in
	    decimal degrees, as for the APERTURE parameter (also fixed
	    a typo: "special extraction" -> "spectral extraction".
	 o  In maxAperture changed default value (indicating no builtin
	    limit) from 180 to 360 degrees since APERTURE is a diameter
	    not a radius.
	 o  Uncommented supportedFrame and modified the definition so
	    that this can be used to specify an allowable frame value to
	    be input via the POS parameter.  The type was changed from
	    anyURI to string.  Added examples of typical values.  Added
	    note that the default if nothing is specified "ICRS".
	 o  In maxFileSize changed the units from bytes to kilobytes
	    for consistency with SSA.
	 o  In the description of complance level changed "TOME" to "TIME".
	    Noted that a compliant service may also return native data.
	 o  In creationType, changed enumeration "specialExtraction" to
	    "spectralExtraction".
	 o  In the description of POS in test query, changed "the size of
	    the search radius" to "the diameter of the search region
	    specified in decimal degrees".
	 o  In the test query generalized the description of POS from
	    "a position in the sky to search" to "search position" as
	    SSA is not limited to sky coordinate frames.
	 o  In the specification of protoSpectralAccess, added a new
	    element "dataModel" to define the data model of the native
	    data returned by the proto service.
	 o  In the specification of protoSpectralAccess deleted
	    defaultMaxRecords and maxAperture since proto spectral services
	    do not support SSA features such as MAXRECORDS and spectral
	    extraction with APERTURE (maxRecords is still defined).
	    Also deleted supportedFrame and "supports" as ICRS can be
	    assumed for proto services, and there are no standard optional
	    service capabilities.  Overall these changes simplify the
	    description of proto services somewhat to match current practice.
	 o  In the specification of protoSpectralAccess changed the
	    maxFileSize units to kilobytes for consistency.
	 o  Many small edits throughout in the description comments.