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Re: [dxwg] Revisiting the definition of "profile" (#963)

From: tombaker via GitHub <sysbot+gh@w3.org>
Date: Mon, 01 Jul 2019 09:26:46 +0000
To: public-dxwg-wg@w3.org
Message-ID: <issue_comment.created-507188969-1561973205-sysbot+gh@w3.org>
[Antoine suggests](https://lists.w3.org/Archives/Public/public-dxwg-wg/2019Jun/0106.html) that the definition of "profile" be modified to read:

    A named set of constraints, which can be based on one or more other identified specifications...

I think we are all in agreement that a profile typically constrains some other (base) specification(s) and we might even accept that a profile is not _necessarily_ based on other specifications.  However, this is not the part of the definition that is problematic.

The biggest problem lies with `named set of constraints`.

None of the examples cited by @pwin above, I would assert, can usefully and accurately be characterized as a "set of" anything, and certainly not as a "set of constraints", especially if the notion of "constraint" is not defined.  The notion of a "named set" does not make the definition any better.

To test whether something a set, it should be possible to enumerate the members of that set.  The [Registered Organization Vocabulary](https://www.w3.org/TR/vocab-regorg/), to take one example, has a list of namespaces used, "Status of this document", header metadata, change log, property and class definitions, usage guidance, Table of Contents, Acknowledgements, References, copyright notice, and the like.  Is it helpful to call this a "set of constraints"?

"Set of" is the language of mathematics and computer science.  An RDF graph can usefully be described as a set of triples.  A Python dictionary can be described as a set of key:value pairs.  But to reduce profiles to "sets of constraints" implies a mathematical rigor to the notion of profile that is quite inappropriate.

As for "constraint": if anything is a constraint, then nothing is a constraint. And if a constraint does not actually "constrain" something, then it fails the test of common sense.

Hence my definition (above) of "data profile" as a "specification" -- not a "set" -- that constrains, extends, or annotates a "data specification".  This definition avoids the thorny question of how to usefully define "constraint".  We can discuss whether a profile MUST refer to another data specification or MAY stand on its own, but that is a different discussion.

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Received on Monday, 1 July 2019 09:26:48 UTC

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