[Bug 3589] Definitions of "schema document" draft proposal for bugs 2822 and 2846 PSVI and processor profiles

http://www.w3.org/Bugs/Public/show_bug.cgi?id=3589





------- Comment #1 from cmsmcq@w3.org  2006-09-06 00:42 -------
For the record, the references given in the description are to
member-only documents, but the same text is visible in the working
draft of 31 August 2006:
http://www.w3.org/TR/xmlschema11-1/#impl-def-list)

Note that the careful distinction Noah is trying to make between XML
documents and infosets is rather undercut by other portions of our
spec, which frequently refer to XML when on Noah's analysis it is of
deep importance that what they really mean is not XML but the infoset
is some XML or non-XML form.  The conformance clause, for example,
defines schema-document aware processors as those which "accept
schemas represented in the form of XML documents" as described in the
spec.  (The 1.0 version of the conformance section was even worse,
since the name it used for schema-document aware processors was
"processors conformant to the XML Representation of Schemas".)

So I observe that the confusion Noah is trying to combat, if indeed it
is a confusion, has deep roots in the existing text.

I have no particular attachment to the wording in the current working
draft, but I do have an attachment to saying that it's
implementation-defined whether an implementation can read schema
documents in XML form, and implementation-defined whether it can read
them in some other form which corresponds to an infoset.

That means I'd prefer not to replace "implementation-defined" with
"implementation-dependent", which means something different where I
come from.  In the QT specs, for example, implementations must
document their behavior for implementation-defined things, but not for
implementation-dependent things; I think it's important that this
property be documented in any claim of conformance, so I want
'defined' not 'dependent'.

And most practical implementations do not actually determine how
schema documents are conveyed to them.  The user does that at
invocation time, by passing schema representations or names of
schema documents in as parameters, or by setting or clearing 
flags which govern the search for components.  
All the implementation does is determine what
possibilities are supported.  So the wording "The exact form in which
XML Schema documents are conveyed to a schema processor is
implementation dependent" seems to me to state a falsehood.

On the general question: I agree with Noah that he tends to see the
infoset as primary and the XML as secondary, a serialization of that
infoset, while I tend to see the XML as primary and the infoset as
secondary, a description of (some of) the information in that XML
document.  I think the infoset spec similarly views the XML as central
and the infoset a secondary, but whether that is so or not, I find the
infoset-centric phrasing proposed in the description of this bug
decidedly confusing.

I think Alternative 2 is promising, though I would prefer that the
definition be the other way round.  So let me propose Alternative 3:

    [DEFINITION:] An -XML schema document- is an XML document or
    element whose information set is a schema document, as defined in
    this specification.

and then

    It is implementation-defined whether a schema processor can read
    XML schema documents, or schema documents in non-XML form.  (See
    Conformance (§2.4), which defines "·minimally conforming·"
    processors as those which cannot read schema documents in XML
    form, and "·schema-document aware·" processors as those which
    can.)

If the WG prefers to avoid making capitalization alone bear the
responsibility for distinguishing important terms, I will be happy (a)
to substitute another phrase ('schema document in XML form' would work
for me, although it's ugly), and (b) to adopt a name for our language
other than "XML Schema", which is a proper noun distinct from a common
noun phrase only by virtue of the capital S ("XSD" works for me, with
or without an official expansion into something like "XML Schema
Definition language").

Received on Wednesday, 6 September 2006 00:43:10 UTC