SSAP sample files

[Ivo Busko]

Hi, Mark

Thanks for catching those errors. Yes, I didn't run the
files thru a XML validator; the only thing I did was to
make shure the "looked similar" to the example in the
SED data model document. My Java IDE also provides some
basic XML validation, and I used that as well. Not enough,
by all means...

I'll fix the errors and re-post the files. Thanks for 
the suggestion on XML validator tools.

Cheers,

-Ivo

> 
> On Tue, 1 Feb 2005, Ivo Busko wrote:
> Ivo,
> 
> Validating these documents against the VOTable schema shows that
> they have a number of errors - they are well-formed XML but not
> valid VOTable documents.  The errors are in two categories:
> 
>   - Many FIELD and PARAM elements lack the required "datatype" attribute.
>     Note that if you have string-valued PARAMs or FIELDs you should
>     use the attributes:
> 
>        datatype="char" arraysize="*"
> 
>     or similar (not just datatype="char" without an arraysize,
>     which means a single character!)
> 
>   - The values of ID attributes are controlled.  First, the value must
>     be an XML name.  Basically this means it must start with a letter
>     or underscore and continue with alphanumerics, underscores, or
>     '.', '-', ':'.  So pathnames are not a good choice.
> 
>     Furthermore, since the ID values identify a single element in the
>     document, they must be unique.  In echelle.xml for instance,
>     several different (though obviously similar) FIELD elements have
>     the declaration 'ID="Coord"' - this makes the XML invalid.
> 
>     Unless you are deliberately trying to identify a single element in
>     the document, for instance to facilitate cross-referencing or
>     an XPath query, it's usually safer to stick with the 'name' attribute.
> 
> I hadn't looked at the SED data model document up till now, but having
> taken a quick look, I note that the missing datatype attribute problem is
> present throughout in the example VOTable serialization presented there,
> so you can't really be blamed for this!  There are many other errors
> in this example too (it is not well-formed XML) - please can they
> be fixed!  I can advise if necessary.
> 
> In both cases, the errors are easy to spot if you run the VOTable
> through an XML validator (checking against the VOTable schema)
> Sun's Multi-Schema XML Validator
> (http://www.sun.com/software/xml/developers/multischema/) is one tool
> that can do this for you, though I'm sure there are others.
> You can check well-formedness (and possibly validate against the DTD,
> though this is not normative at VOTable 1.1) using other tools such
> as xmllint which comes with RedHat Linux.
> Can I encourage people who are publishing VOTables in documentation
> or as data providers to do so!
> 
> Mark
> 
> --
> Mark Taylor    Starlink Programmer     Physics,  Bristol University, UK
> m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/