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   Re: [xml-dev] What kind of trap is XPointer?

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"bryan" <bry@itnisk.com> writes:

> Simon St.Laurent wrote:
> >It might be sensible if a bit odd to create application/psvi or
> somesuch
> >for applications of XML which rely on the PSVI, but that's just one
> >possibility.
> This addresses something I was wondering about earlier but I don't think
> I necessarily expressed that well. Maybe you can explain this to me, if
> you care to and if you think it can be simply stated:
> How are we supposed to know when an XML document is also a PSVI? I mean
> I know how I would know this in the context of my application
> environment, I would keep track of it, and it seems to me that some
> environments will be built that do this for me(and I will probably hate
> them), but is there supposed to be some "higher-level" method for doing
> this track-keeping. What this might be I don't know,
> processing instructions, a mimetype as discussed above, or is this being
> left as a separate issue?

The PSVI is not as defined a document in the sense I think you mean it
(an encoded character sequence satisfying at least the well-formedness
requirements of XML 1.0 plus Namespaces).  Neither is the (vanilla)
Infoset.  So your question doesn't quite make sense.

Infosets in general, including both vanilla and PSV, are abstractions
over possible representations of the information content of XML
documents.  Any implementation of an XML processor which claims to be
(vanilla) Infoset-conformant must mean by that claim that it provides
an interface to and/or representations of an advertised subset of the
Information Items and Properties defined in the Infoset REC [1] for
the documents it processes.  Any conformant implementation of the W3C
XML Schema REC [2] likewise must provide an interface to and/or
representations of at least the vanilla and PSV Information Items and
Properties for the documents _it_ processes, as specified in that REC.

Given all that the short answer to your question is:  if you're an
application and some library or sub-part gives you a handle on
something which purports to be a conformant Infoset of some kind, if
you find a [validation root] property on the Element Information Item
which is the sole child of the Document Information Item therein, you
know that it's a PSVI -- if you don't, it _probably_ isn't.  (It's
possible that only a sub-tree of your document got
schema-validity-assessed, but if that's possible you'll probably know
about it, and know to look through the document for the validation

More than you wanted, I suspect :-)


[1] http://www.w3.org/TR/xml-infoset/
[2] http://www.w3.org/TR/xmlschema-1/
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
 [mail really from me _always_ has this .sig -- mail without it is forged spam]


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