Elements to add to TabularSkyService

[Ray Plante]

Hi Martin,

On Thu, 1 Jul 2004, Martin Hill wrote:
> <PrimitiveType> 

[Elizabeth responded to this.]

Re: <ucd>  

I would recommend keeping the same ucd element.  We can add an optional 
attribute that indicates the UCD version with an appropriate default.  

> <ErrorColumn> - an optional element with a value of the column name, 
> that holds the error for the values in this column.

I'm concerned that, given our past discussions (on this and other lists)
that this one is not sufficiently well defined to be added to the schema
now.  This discussion came up wrt VOTable, and it was recognized as one of 
a general problem of associating columns.  Column groups were the answer.

I urge other people to comment on this.  The relevant question that 
comments need to address is, should we add ErrorColumn at this time?  We 
could add it now as a "simple but useful" solution with the possibility of 
having to yank it out later.  (I'm less worried about this kind of 
volatility in VODataService.)

Regardless, I encourage you to post your update to VOResourceV010Disc
(perhaps just include the new definition of the Param type);  it's a lot
easier to discuss when we have something concrete down.

If we do not incorporate ErrorColumn into the WD release this week, our 
alternatives are:

  o  add it into a new internal draft for further discussion, prototyping, 
       and later release.  
  o  define it in a local AstroGrid extension.  This extension need only 
       define the extension to the Param type.

cheers,
Ray