RE: [xml-dev] Your XML documents may use different sets of characters, d

["Costello, Roger L." <costello@mitre.org>]

Hi Ken,

CREPDL looks promising.

Having control over what characters are allowed in XML documents is precisely what I am seeking.

Do you know if CREPDL works with XML Schemas?

/Roger



-----Original Message-----
From: G. Ken Holman [mailto:gkholman@CraneSoftwrights.com] 
Sent: Tuesday, May 17, 2011 9:30 AM
To: XML-Dev Mailing list
Subject: Re: [xml-dev] Your XML documents may use different sets of characters, depending on which implementer you select?

At 2011-05-17 09:10 -0400, Costello, Roger L. wrote:
>The XML specification mandates version 2.0 of Unicode.

Ummmmmmm .... that isn't my read.

  http://www.w3.org/TR/2008/REC-xml-20081126/
  Unicode
  The Unicode Consortium. The Unicode Standard, Version 5.0.0, defined
  by: The Unicode Standard, Version 5.0 (Boston, MA, Addison-Wesley,
  2007. ISBN 0-321-48091-0).

Furthermore, it is now open-ended so as to allow future versions of 
Unicode to implicitly be valid in XML documents:

  Almost all characters are permitted in names, except those which
  either are or reasonably could be used as delimiters. The
  intention is to be inclusive rather than exclusive, so that writing
  systems not yet encoded in Unicode can be used in XML names.

>Are other XML applications similarly lax, permitting implementers to 
>pick which version of Unicode they will support?
>
>Does the XSLT spec allow implementers freedom to choose which 
>version of Unicode they will support?
>
>Does the UBL spec allow implementers freedom to choose which version 
>of Unicode they will support?
>
>Does the RELAX NG spec allow implementers freedom to choose which 
>version of Unicode they will support?
>
>Does the XBRL spec allow implementers freedom to choose which 
>version of Unicode they will support?
>
>Does the SVG spec allow implementers freedom to choose which version 
>of Unicode they will support?

My guess is the above is all moot.  As I understand it, XML allows 
any Unicode character (now or defined in the future) to be 
used.  Those specifications would simply cite XML and not impose

Now, if the purpose of your question is to prevent a processing 
system from having to process unknown or unsupported Unicode 
characters, check out the ISO/IEC 19757-7 CREPDL - Character 
Repertoire Description Language:

  ISO/IEC 19757-7:2009 specifies a Character Repertoire Description
  Language (CREPDL); a CREPDL schema describes a character repertoire.
  ISO/IEC 19757-7:2009 introduces kernels and hulls of repertoires,
  then specifies the syntax of CREPDL schemas and the semantics of a
  correct CREPDL schema; the semantics specify when a character is in
  a repertoire described by a CREPDL schema. ISO/IEC 19757-7:2009
  defines CREPDL processors and their behaviour. Finally, it describes
  differences of conformant CREPDL processors, and provides examples
  of CREPDL schemas.

Using a character repertoire schema you can validate an instance for 
having only the Unicode characters you want it to have.

I hope this helps.

. . . . . . . . . . . . . Ken

--
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