MIVOT: fully qualified attribute names

[Paul Harrison]

> On 23 Feb 2023, at 14:24, Laurent Michel <laurent.michel at astro.unistra.fr> wrote:
> 
>>> I understand, but there is no reason but he common sense, to give a particular structure to the VOMDL-IDs. 
>>> We you generate VODML from XMI (modelio), you first get random IDs for the VOMDL-ID and in a second steps, there are built from [model-name, attr-name , ID of the host class], but the XSLT doing this is not part of the standard. If you edit your VOMDL by hand, like Pat did, you may introduce a distortion to this rule without breaking the schema compliance.
>>> 
>>> This is why I suggest to tell the users:
>>> - do not rely on names
>>> - do no parse VODML-IDs
>> 
>> I agree that technically the VODML-IDs are just XMLIDs andlong as they are unique within a single VODML instance that they can have any value/structure. However, this is precisely the problem, as simply regarded like this, then two instances of a VO-DML document describing a particular model could both be valid, but with entirely different sets of VODML-IDs, and in this situation another standard like MIVOT cannot use those VODML-IDs without also saying precisely which instance document is being used to describe the model. Unless there is some guarantee about the form of the VODML-ID  then there could also be undesirable behaviour that new versions of a model did not retain the exact same VODML-ID for a particular attribute.
>> 
> 
> I do not agree with this. Once the VODML-IDs have been set, no matter how you do it, they are part of the standard - of the VOMDL description of the model -. None is allowed to change them later on.
> 

The VO-DML standard makes no guarantee of this - it is perfectly legal for me to create the next version of the PhotDM for instance with totally different VODML-IDs. We all agree that it is sensible that a particular model element keeps a constant ID and better that it is human readable, and that the human can look at the structure of the VODML-ID and make inferences about the function of that element in the model. However, the only reason that this has happened in model instances so far is because of the XSLT processing, which you say is not part of the standard. I would like the structure that the XSLT scripts impose to be part of the standard, so that the manual edit that Pat did would actually be non-compliant.

From a pragmatic point of view there are only of order 10 VO-DML instances in existence in the universe, so we can easily make any compliant, but as I think the majority of these were produced with the XSLT scripts, then they will be compliant with the technically more restrictive definition of the VODML-IDs that I am proposing anyway.

Looking at the VO-DML schema, I was wrong to say above that the VODML-ID elements are XMLIDs as of course the VODML-REFs actually do have some structure imposed on them in that they have the model name as a prefix to the reference - so the reference validation is not done by the XML Schema mechanisms at all, but is done at the schematron level.

Paul

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