Changes to VOTable 1.4 Working Draft

[Tom Donaldson]

Dear Apps,

After some discussion about the Working Draft for VOTable 1.4, I believe we have some changes that are ready to be folded into the draft.  Markus will make the first two edits, then, pending comments or objections, I will add the other changes and push a new draft out at the end of the week.  Note that item #11 hasn't really been discussed yet, so let the comments fly, either now or after the next draft is ready.

Regarding the proposal to require "ref" for uses of TIMESYS (http://mail.ivoa.net/pipermail/apps/2019-February/001335.html ), I don't think it's been resolved, but opinions so far are more in favor than against.  If you have a strong opinion, please make that known soon.

Regards,
Tom

Changes for next draft:

1) (Markus)  Remove references to STC, which were rendered obsolete by Erratum 1.3-1.

2) (Markus)  Add a reference to the XMLVers Endorsed Note to the discussion about the distinction between namespace URIs and schema URLs.

3) (Mark - already done)  Improve the colouring in figure 4.

4) Section 3.5: reword the sentence:
The TIMESYS element defines such a time system and gives itself the identifies itself with ID="time frame".
to
In the example, the TIMESYS element describes that time system.  The TIMESYS ID value just needs to be unique within the document so that it can be referenced by FIELDs or PARAMs.

5) In the section 3.5 TIMESYS example, remove the ID values from the FIELDs since they are not used.

6) Section 3: replace 
"Documents claiming to represent VOTables must include the reference to the VOTable schema"
with 
"Documents claiming to represent VOTables must validate against the relevant version of the VOTable schema without error"

7) Section 3:  Remove xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" from the required attributes for the VOTABLE element, since it is not required, especially since we won't require the schema location.  (see #6)

8)  Add indentation in the xsi:schemaLocation examples to improve readability.

9)  Replace the claimed REC status of the document with the appropriate Working Draft disclaimer from the DocStd appendix.

10)  In sections 4.3 and 4.4, add references to DALI and VOUnits respectively since those standards came about since the writing of VOTable 1.3.  Also mention those resources in section 1.4.

11)  In section 3, along with the changes from #6 and #7, I think a brief discussion of xsi:schemaLocation may still be useful (but I could be talked off that if people find it unhelpful or too confusing).  I propose modifying the wording of the text at the end of the section to:

Neither the VOTable nor XML standards require specifying the VOTable schema location within the VOTable document.  However, providing the schema location enables some XML parsers and editors to do automatic schema validation.  To do so correctly during and after the VOTable 1.4 approval process, follow these guidelines:

Before VOTable 1.4 becomes recommended, use these VOTABLE attributes to reference the version 1.4 schema: 

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.ivoa.net/xml/VOTable/v1.3
                  http://www.ivoa.net/xml/VOTable/votable-1.4.xsd"

Once VOTable version 1.4 becomes recommended, the following schema reference will be upward compatible until the next major version (2.0):

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.ivoa.net/xml/VOTable/v1.3
                  http://www.ivoa.net/xml/VOTable/v1.3"