VEP-007: datalink-core#detached-header

[Laurent Michel]

Hello,

I agree with you Anne, except for the last sentence :-)

In the Datalink context, I think it is important to keep seperate words for #meta-data and #documentation.
#documentation relates to textual information on #this. A good example is given by the Vizier READMEs that provide the 
scientific contexte of #this.
#metadata relates to a documentation that is required to process #this, e.g. WCS.

One is supposed to be read by the user whereas the other is meant to by used for some processing.

Laurent


Le 15/09/2021 à 13:03, Anne Catherine Raugh a écrit :
> Hello,
> 
> Well, thinking about this at 6am without having had coffee yet...
> 
> In the context of data, "documentation" and "metadata" are very nearly synonymous. The term "machine-readable" meant something 
> quite different when I started in this business (back when dinosaurs roamed the Earth providing tech support), but now it seems 
> to have evolved to mean what we would have called "machine-actionable". Even still that's not as clear a line as we might like.A 
> PDF document, for example, is machine-readable: it takes a computer to turn it into something that is human-readable and it is 
> also possible to extract text, tables, and other items from a PDF file. But I don't think anyone wants to see PDF headers for 
> data. Machine-readable headers are often human-readable as well, by design (like FITS).  (There are binary headers out there in 
> some formats that are /not/ human-readable, but I suspect they do not show up in IVOA repositories as data files.)
> 
> So, from my still-learning and yet aging perspective, I would expect that "documentation" would be the broadest term, that 
> "metadata" would be a subtype of documentation with the stipulation that it is documentation provided in a format that conforms 
> to a published standard that makes it machine-readable. "Header" would then be a subtype of "metadata" that is tightly bound to 
> #this, with the further restriction that it provides some metadata that is unique to #this (otherwise why carry it along?). If 
> we have a need to identify documentation that is not machine-readable (PDFs would qualify in the IVOA context), then there is 
> probably another subtype of #documentation lurking in the wings. If we require that all documentation be machine-readable, then 
> "documentation" and "metadata" are synonymous in the IVOA context, and there is no need for two terms.
> 
> Coffee time...
> 
> -Anne.
> 
> 
> On Wed, Sep 15, 2021 at 5:26 AM BONNAREL FRANCOIS <francois.bonnarel at astro.unistra.fr 
> <mailto:francois.bonnarel at astro.unistra.fr>> wrote:
> 
>     Hi all,
>              I know that VEP-007 will be discussed today and I will not
>     participate.
>              I got no answer to this email except recently from Markus in a
>     private discussion.
>              I am strongly in favor of the new term itself.
>              My small concern (with a proposal) is that as it is stated now
>     in "https://volute.g-vo.org/svn/trunk/projects/semantics/veps/VEP-007.txt
>     <https://volute.g-vo.org/svn/trunk/projects/semantics/veps/VEP-007.txt>"
>              The head-term of #detached-header is "documentation".
>              I think that a head term like #metadata would be better.
>              This term doesn't exist  up to now and I think it is  lacking.
>              #metadata is different from #documentation in the sense that the
>     first one is machine readable while the other one is human readable
>              So usage by clients would be very different. Other example for
>     #metadata would be #ivoa-provenance-metadata and #ivoa-obscore
>              If you think this is a good idea I would like to add this term
>     either in the same VEP or as another VEP with the small modification of
>     head-term in VEP-007 itself
>     Cheers
>     François
> 
>     Le 16/06/2021 à 09:20, BONNAREL FRANCOIS a écrit :
>      > Hi all,
>      > Very interesting proposal indeed.
>      > I'm just wondering if we could take the opportunity to create a new
>      > #metadata branch .
>      > So that "#detached-header" would be a child of this head term #metadata
>      > Other children terms in the future could be #provenance_record (to
>      > attach ivoa provenance serailisation to #this), #obscore_record (to
>      > attche obscore metadata to #this when the dataset was not discovered
>      > via an ObsCoredelivering service) etc ....
>      > Cheers
>      > François
>      > Le 16/06/2021 à 09:13, Baptiste Cecconi a écrit :
>      >> Hi all,
>      >>
>      >> I received an direct comment from Anne Raugh, and have updated the
>      >> Rationale of VEP-007 accordingly. I copy the new content of the
>      >> Rationale section below:
>      >>
>      >>> Rationale:
>      >>> In some formats and archives, the metadata required to decode the
>      >>> content of #this is in a separate file. In the case of NASA/PDS
>      >>> data products, for example, the PDS label file contains the decoding
>      >>> metadata. In some archives, the FITS header may be stored separately
>      >>> as a plain text file, next to a data file consisting of a binary
>      >>> stream of bytes. Clients would use the content type (MIME type)
>      >>> (e.g.: application/x-pds4-label+xml, or text/x-pds3-label) to enable
>      >>> the processing.
>      >>>
>      >> Cheers
>      >> Baptiste
>      >
>      >
> 

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Laurent Michel
SSC XMM-Newton
Tél : +33 (0)3 68 85 24 37
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Université de Strasbourg <http://www.unistra.fr>
Observatoire Astronomique
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