[TAP] draft 0.42

[Patrick Dowler]

On Monday 27 April 2009 07:04:51 Francois Ochsenbein wrote:
>Sorry for the length of this message -- I tried nevetheless
>to be as brief as > possible in the enclosed comments related
>to TAP Version 0.42. Some comments are just typos, but a
> couple imply VOTable adjustments:
>
> ==> the usage of the <INFO> tag (sec. 2.9): should we (I mean the
>       VOTable group) give up with the addition of sub-elements
>       like <DESCRIPTION> in <INFO>, which are included in VOTable1.2 ?

This is in reference to placing content directly inside the INFO element 
rather than using a child DESCRIPTION? If VOTable requires the child element 
then the examples should be changed to comply. This section was not meant to 
suggest a VOTable change, just how to use existing features. So, it should 
have a child DESCRIPTION rather than child content?

> ==> the 'format' as a new attribute of <FIELD> (and therefore
>       of <PARAMETER>): I assume this word is replaced by 'encoding',
>       with a similar meaning of what is proposed in Apx A.5 of
>       VOTable1.2. Is that agreeable ?

I was thinking some more about format vs encoding... The encoding as used in 
A.5 is a way to encode binary as text and does not specify the format (of the 
actual value). For example, one would would normally describe a graphic file 
with (not specifically VOTable here):

encoding="base64" format="image/png"

So, despite my own suggestion, I think format and encoding should remain 
distinct (also consistent use of the terms in http: content-type aka format 
and content-encoding). 

The use/meaning of encoding in A.5 could remain unchanged, although it would 
be nice to be able to put it once in the FIELD rather than in every TD.  I 
would go back to Mark's original suggestion of a format attribute (for FIELD 
and PARAM), which TAP would use like this, for example:

<FIELD datatype="char" arraysize="*" format="STC-S" />

to describe a region column, or 

<FIELD datatype="char" arraysize="*" format="ISO8601" />

to describe a timestamp column. One could in principle store a graphic file in 
a BLOB or varbinary column and describe it as:

<FIELD datatype="unisgnedByte" arraysize="*" 
  encoding="base64" format="image/png" />

assuming the proposal in A.5 is also adopted and encoding is allowed in the 
FIELD and not just the TD.

>==================================
> Comments on [TAP] draft 0.42
>==================================

Thanks for all the detailed fixes; I will include asap.

-- 

Patrick Dowler
Tel/Tél: (250) 363-0044
Canadian Astronomy Data Centre
National Research Council Canada
5071 West Saanich Road
Victoria, BC V9E 2M7

Centre canadien de donnees astronomiques
Conseil national de recherches Canada
5071, chemin West Saanich
Victoria (C.-B.) V9E 2M7
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