Re: (Partial) review of Versioning XML

Norm Walsh writes:

> I think that's just a definition of XML. I'd expect a language to
> have some extra-syntactic constraints too:

Yes, I would expect it to be some subset of well-formed XML.

> a grammar of some sort.

No, not in general if you mean an intensional grammar, though certainly 
very often.  I see nothing wrong with defining a language by enumeration 
of the instances, by suggesting that anything that meets certain 
Schematron constraints is in, etc.  If you mean grammar in that broader 
sense of:  some syntactic constraints we can talk about, then yes.  If you 
mean grammar in the narrow sense of something we can write down in closed 
form using regexs, EBNF,  regular trees (RelaxNG), content models, etc., 
then not necessarily.

In short, I wouldn't emphasize the grammar:  I'd emphasize that it's a 
subset of well formed XML, and typically (though not necessarily) defined 
so that the instances have something common in form or purpose.  Aside: 
though I suppose you could have a language that is the union of all 
symphonies and shopping lists, I think we don't need to go there;  then 
again, we can talk about the language of all instances of any sort that 
just happen to have a version attribute on the root, or an xml:lang 
attribute on the root, even if we're talking about both shopping lists and 
symphonies.  We can design document management systems that will manage a 
wide variety of things, if just a few attributes are maintained in common 
among them.  That is an important use case, IMO.

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------

Received on Wednesday, 30 May 2007 14:09:16 UTC