canonical lexical representations of derived types

Hi.

 Does the notion 'canonical lexical representation'
make sense for types derived from built-in types
(types described in XML Schema Part 2: Datatypes)?

If does not:
what does the "XML Schema Part 1: Structures" mean saying:
---------------
3.3.4 Element Declaration Validation Rules
...
5.1.1 If the ·actual type definition· is a ·local type definition· then the 
canonical lexical representation of the {value constraint} value must be 
a valid default for the ·actual type definition· as defined in Element 
Default Valid (Immediate) (§3.3.6).
---------------

If does:
where is the notion defined?

For example:
What is a canonical lexical representation of 1.0 
with the type defined as follows:
  <simpleType name="Float">
      <restriction base="float">
          <pattern value=".*"/>
      </restriction>
  </simpleType>

Thanks.
-Evgueni


> From: "Nagy, Marton" <MARTON.NAGY@saic.com>
> To: jeni@jenitennison.com
> Cc: www-xml-query-comments@w3.org, jmarsh@microsoft.com
> Date: Tue, 22 Jan 2002 16:00:13 -0500
> Subject: Re: Data Model WD - canonical lexical representations
> 
> Hi Jeni,
> 
> Thank you for catching these. We will add an issue entitled
> "Lexical representation of Schema primitive types" for tracking
> purposes. We will take this up with XML Schema and work with them
> to define the canonical lexical representation for these types.
> 
> Regarding xs:QName, we are currently working on various
> namespace related issues including the ones that effect canonical
> lexical representation and hoping to include the resolution of them
> in our next draft.
> 
> Best regards,
> Marton Nagy
> 
> >
> > Date: Sun, 13 Jan 2002 14:21:37 +0000
> > From: Jeni Tennison <jeni@jenitennison.com>
> > Message-ID: <58539046948.20020113142137@jenitennison.com>
> > To: www-xml-query-comments@w3.org
> > Subject: Data Model WD - canonical lexical representations
> >
> > Hi,
> >
> > Looking at the string-value accessor for simple typed values - while I
> > think it's right to use the canonical lexical representation of the
> > values, unfortunately the XML Schema Datatypes Rec doesn't detail the
> > canonical lexical representation of all of the primitive types. In
> > particular, no canonical lexical representation is specified for:
> >
> >   - xs:string, xs:base64Binary, xs:anyURI (but that's OK, I think we
> >     can guess)
> >
> >   - xs:duration - presumably the lexical representation contains all
> >     components of the duration (years, months, days, hours, minutes
> >     and seconds, even those that occur 0 times? Or are these omitted?
> >     In the latter case, what's the canonical lexical representation of
> >     PT0S? Since the number of seconds can be a decimal, is this
> >     decimal represented with a decimal point (i.e. using the canonical
> >     lexical representation for xs:decimal)?
> >
> >   - xs:date - what happens to the timezone component? Presumably,
> >     unlike xs:dateTime and xs:time, this isn't normalized to Z?
> >     (And similarly for xs:gYearMonth, xs:gYear, xs:gMonthDay,
> >     xs:Month, and xs:Day)
> >
> >   - xs:QName and xs:NOTATION - these are the trickiest (their value
> >     spaces are the same). The XML Schema Rec states that the lexical
> >     representation of a QName depends on the in-scope namespaces. When
> >     you're doing a query/transformation, which namespace declarations
> >     do you use - the ones in the query/stylesheet or the ones from the
> >     source document? What if there's more than one namespace
> >     declaration for the namespace URI? What if there aren't any?
> >
> >     The difficulty with using the original prefix for the QName is
> >     that the definition of a canonical lexical representation is that
> >     two equal values have exactly the same canonical lexical
> >     representation. Equality of QNames should be based purely on the
> >     namespace URI and local name, not on the prefix. One possibility
> >     would be to introduce something like:
> >
> >       {namespace-uri}local-name
> >
> >     but this is not, of course, a valid lexical representation of a
> >     QName.
> >
> >
> > Cheers,
> >
> > Jeni
> > ---
> > Jeni Tennison
> > http://www.jenitennison.com/
> >
>

Received on Friday, 5 April 2002 09:16:29 UTC