Re: [xml-dev] SGML default attributes.

[Steve Newcomb <srn@coolheads.com>]

On 05/07/2016 02:42 AM, Liam R. E. Quin wrote:

> one
> limitation is how to capture (without resorting to ad hoc comments)
> some constraints that are beyond the expressive power of the grammar
> or are contingent in some way.  I believe Schematron is still the
> only system to take this seriously.

To some extent XSD does too, by allowing embedded Schematron rules :-)
or other extension mechanisms. DTDs do too, using processing
instructions, although it's terribly underspecified.

And HyTime uses Architectural Forms for HyTime-defined DTD-constraint-specification extensions, and it also flings the door wide open for other universes of constraint specifications to co-exist side-by-side, alongside the HyTime-defined constraint-specification extensions, or altogether without them. 

When we mess with a document that straddles N universes of constraint-specification, we shouldn't have to first pretend that it occupies space in only one of them at a time in order to test the validity of some component in each of them.  We should be able to take a broader view, working in a meta-universe that contains all of the document's universes.  In shuch a meta-space, we can comprehensively validate each individual component of such a document, in its living context.

In order to make it possible for SGML documents to occupy space in multiple universes of discourse simultaneously, HyTime specifies the use of NOTATION declarations, one per universe. 

In order to take multiple universes of NOTATION seriously, I think we also have to take seriously the notion that entities can identify universes of discourse.  FWIW, HyTime declares both SGML and itself as NOTATIONs, referencing those ISO standards in the usual formal-public-identifier fashion. 

BTW, you don't have to be ISO to style yourself as an authority suitable to be cited in a formal public identifier (FPI).  Anybody can do that.  No internet domain name is required, but such a thing could, of course, be used. 

It's interesting that, according to https://en.wikipedia.org/wiki/Formal_Public_Identifier, W3C has never registered the owner identifier it uses for itself, "W3C".  If that's true, I guess W3C recognizes only its own notation-universe's authority for owner identification, rejecting that of the United Nations.  I could digress here into discussion of the relationship of universes of discourse and human-community-identity, war, and religious fundamentalism, but I think I'll confine myself to the conjecture that we'd all be a lot better off if we simply adjusted to the fact that we are not the center of the one-and-only universe, and we will either adapt to that fact or die.  It's a Copernican revolution that still lies somewhere in the future, if anywhere at all.
 
Steve