Changes to VOTable 1.4 Working Draft

[Mark Taylor]

On Fri, 15 Feb 2019, Markus Demleitner wrote:

> On Thu, Feb 14, 2019 at 04:23:59PM +0000, Tom Donaldson wrote:
> > A stand-alone validator *should* care about minor versions,
> > validating against the schema identified by the version attribute.
> > For example, if my VOTABLE has version="1.3" and also includes a
> > TIMESYS element, then ideally a validator would flag an error.
> 
> That is a reasonable use case, that, as far as I can see, is not
> sufficiently addressed in the XML Versioning Policies so far.

...

> though.  I'm also pretty sure custom validators are possible without
> any hacks with what we have in VOTable, viz,
> 
> * http://ivoa.net/xml/VOTable/votable-1.4.xsd  as the location of
>   the machine-readable schema; this would, for instance, be hard-coded 
>   into the validator as the schema associated to @version="1.4"[1]
> * <VOTABLE version="1.4" xmlns="http://ivoa.net/xml/VOTable/v1.3">
>   as the root of production VOTables.
> * An (ideally unversioned) reference to XML Versioning Policies where
>   the scheme is explained in more depth for those needing to dig in
>   deeper.
> 
> [1] I'd argue hard-coding "official" schema URIs into software is
> what we want to do here, anyway.  Alternatives I could come up with:

FWIW votlint, the STILTS votable validator (also found in taplint)
hard codes the schema content (it has internal copies of the VOTable
XSD) for each known VOTable version.  So yes custom version-specific
validation is possible, but that doesn't help you if you want to perform
minor-version-specific validation of VOTables using generic XML tools,
which I think is what Tom has in mind.

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/