Standardising units and formats (and ref frames?) in transmission

[Doug Tody]

If we are talking about general tables (external data) then I suggest
we merely define some recommended guidelines for data providers
to follow.  Mandating how arbitrary columns of arbitrary external
tables are presented is not going to work.  An exception would be
that we could mandate the unit and representation for a subset of
key important UCDs, e.g., the designated main RA and DEC columns of
a table, if given.  Achieving uniform standards for a few key bits
of metadata is achievable and would have a big impact.

Regarding sexagesimal (for coordinates not ISO times) - we forbid this
in VO data models.  However for an external catalog I would hestitate
to mandate that existing character string columns containing encoded
positions be changed.  Rather it would be sufficient to add new columns
in fixed units and representation.  Again, if we forbid us of certain
UCDs unless certains units and representation are used, this would
pretty much solve this problem while still allowing pass-through of
the original table data.

 	- Doug


On Mon, 18 May 2009, Roy Williams wrote:

> I agree with Alberto that restricting the diversity of units is a very 
> effective strategy, easier and perhaps more effective than building complex 
> infrastructure to handle that diversity.
>
> Proposal: As a first step, perhaps we could agree to have "No Sexagesimal 
> Inside"?
>
> Note: While users will see sexagesimal in the VO, it should always be created 
> at the final, presentation stage, along with the choice of font sizes and 
> colors. While users will be able to input sexagesimal in the search boxes, it 
> should always be converted by the browser to decimal before going to the 
> server.
>
> Consequence: Given that VOTable always needs conversion before a human sees 
> it, the proposal implies no VOTable or database should have any sexagesimal 
> notation anywhere in it.
>
> Right?
> Roy
>
>