New VOTable 1.4 WD (2019-03-18)

François Bonnarel francois.bonnarel at
Wed May 8 16:48:21 CEST 2019

Hi all,

I have been lately reading the draft and note page. Thanks for this work.

I only make here a few comments.

    1 )  delaying refposition attribute in COOSYS. I understood that 
Arnold has strong arguments that when we have COOSYS and TIMESYS they 
would have to share the same refposition which is something will should 
be explained clearly in the text in case this COOSYS addition would have 
been validated. I also understand that as a matter of consequence the 
refposition in TIMESYS is also valid for an associated COOSYS. But in 
case we only have COOSYS, this refposition is strongly missing. So if we 
delay that to 1.5 we should at least reinforce he need for this change 
in the Notes.

   2 ) People here at CDS have been playing around the TIMESYS with 
example taken in VizieR. This really shows that in many cases a 
"double"-valued (or more) ref should be a great help. The solution could 
be to change the definition of ref in VOTable schema from IDref to 
IDrefs. This was discussed at the time of the TIMESYS note was made 
public and Mark T said it could have consequences to be addressed. Such 
a mechanism could also enter in competition with "ref" set on GROUPS. So 
I agree this may be a too long discussion. But this should be set in the 
Notes as something to tackle in version 1.5

    3 ) decimal years representations in 3.5 : usage of besselian or 
julian years for timestamps apart from making timeorigin un-useful (and 
then forbidden) also implies some inference on the timescale used (see 
the TIME WCS paper for references and discussion). I suggest to add the 
the following sentence at the end of "timeorigin" explanation: "When 
using calendar epochs written in yr or Ba, note that conventionally 
Julian years are tied to the TDB timescale and Besselian years to ET 
(written here as TT) (Rots and Bunclark et  al., 2015)."

      By the way, on a related topic  I discover that in 3.4 COOSYS, we 
don't explicitly constrain the representation of time in equinox and 
epoch attributes. This however clear in the xml schema. I suggest adding 
after "... the epoch of the positions if necessary", the following 
sentence: " Both equinox and epoch MUST be expressed in the Julian or 
Besselian calendar".

     4 ) I took the opportunity to check all the spec even for the parts 
which didn't change since a while.

             I found two little typos. Page 11 . section 3.2, we have 
"...represents therefore a a valid name".

                         Page 22 section 5.2 "...a cell value flagged as 
null is filled with with the NaN value...".

            IN addition figure 4 is  colors four digits in pink as null 
flags, while we have 6 fields in the two examples rows.



Le 22/03/2019 à 21:46, Tom Donaldson a écrit :
> Thanks for the review, Mark.  I’ve added these as proposed changes to the notes on .  Assuming there are no objections, I'll make the edits soon in volute, and they'll make it into the next version we publish.
> Cheers,
> Tom
> On 3/22/19, 2:38 PM, "Mark Taylor" <M.B.Taylor at> wrote:
>      Tom,
>      a few very minor things I've spotted this time round.
>      I don't think they warrant a new WD, but you could make the edits or
>      make a note of them for next time the document gets updated.
>      Sec 3:
>         "documents may include schemaLocation attribute"
>          -> "documents may include the schemaLocation attribute"
>         (or "a" or "some" ...)
>      Sec 3.5:
>         "A \elem{TIMESYS} element referenced via a ref attribute MUST..."
>         -> "A \elem{TIMESYS} element referenced via a \attr{ref} attribute MUST..."?
>      Sec 4.1, item concerning the ref attribute:
>         "(reference to the GROUP attribute which specifies the coordinate frame)"
>         -> "(reference to the COOSYS attribute which specifies the coordinate frame)"
>      Sec 5:
>             <INFO name="HISTORY">
>             The very first Virtual Telescope observation made in 2002
>             </INFO>
>          I've just noticed this is not legal - the value attribute
>          (optional at VOTable 1.0 but mandatory since VOTable 1.1)
>          is missing.  It should read:
>             <INFO name="HISTORY"
>                   value="The very first Virtual Telescope observation made in 2002"/>
>          But that mistake has been there for a long time, so you may choose
>          not to make the edit this time round.
>      Also, probably the "STC" reference in figure 1 should be removed now.
>      Can't remember if I mentioned it before; if the problem is that
>      it's too hard to edit the PDF graphic, fair enough, forget I said it.
>      Mark
>      On Wed, 20 Mar 2019, Tom Donaldson wrote:
>      > Hi All,
>      >
>      > There is new working draft for VOTable 1.4 available for review at:
>      >
>      >
>      > There is a chance this is the last WD we will have for 1.4, so please review it soon so that corrections can be incorporated well before the Interop meeting.  I will collect suggestions on the wiki, which also tracks the changes made so far and proposals for the next VOTable version (likely 1.5):
>      >
>      >
>      > From the wiki page above, here is the summary of changes for this working draft:
>      >
>      > - Miscellaneous cleanup edits. (see )
>      >
>      > - Remove unused namespace declarations from examples. (see )
>      >
>      > - Make footnotes visible in HTML (already correct in PDF)  (see )
>      >
>      > - Require "ref" for uses of TIMESYS (see )
>      >
>      >
>      > Regards,
>      > Tom
>      >
>      >
>      >
>      --
>      Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
>      m.b.taylor at +44-117-9288776

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