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AssocSS issue 15 (was Re: Minutes for XML Core WG telcon of 2009 July 1)

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Wed, 01 Jul 2009 18:42:09 +0100
To: public-xml-core-wg@w3.org
Message-ID: <f5bk52sxpu6.fsf_-_@hildegard.inf.ed.ac.uk>
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Grosso, Paul writes:

> ACTION to Henry:  Propose a solution to issue 15 (the productions)
> in email, possibly using a xref to the XML spec itself.

Issue 15 reads:

    15. Modify the grammar productions

    Change production [1] to only include the processing instruction's
    data and not the leading "<?xml-stylesheet " or trailing "?>"
    . This would allow reuse of the syntax for other specs
    (e.g.. XBL2). Also, an xml-stylesheet processor would generally
    only see the PI contents after the XML parser has parsed it as an
    XML PI.

Production [1] looks like this:

    [1] StyleSheetPI ::= '<?xml-stylesheet' (S PseudoAtt)* S? '?>'

The relevant part of the XML spec is here [2]:

   Processing Instructions

    [16] PI ::= '<?' PITarget (S (Char* - (Char* '?>' Char*)))? '?>'
    [17] PITarget ::= Name - (('X' | 'x') ('M' | 'm') ('L' | 'l'))

    PIs are not part of the document's character data, but MUST be
    passed through to the application. The PI begins with a target
    (PITarget) used to identify the application to which the
    instruction is directed. The target names " XML ", " xml ", and so
    on are reserved for standardization in this or future versions of
    this specification. The XML Notation mechanism may be used for
    formal declaration of PI targets. Parameter entity references MUST
    NOT be recognized within processing instructions.

I think what we should do is move towards something like the
following:

    [1] StyleSheetPI ::= PI (linked to REC-xml#NT-PI)
                     ::= '<?xml-stylesheet' PIBody '?>'
                         [That is, an xml-stylesheet processing
                          instruction *must* satisfy _both_ productions]

    [1a] PIBody      ::= (S PseudoAtt)* S?

    . . .

This has the advantage of retaining the anchor in the existing spec.

We could alternatively try doing something with prose:

 [Definition: An *xml-stylesheet processing instruction* is an XML
  processing instruction (ref. REC-xml#NT-PI) whose PITarget is
  'xml-stylesheet' and the remainder of whose content satisfies the
  following BNF:

    [1] PIBody      ::= (S PseudoAtt)* S?

    . . .

where the definition would have NT-StyleSheetPI as its name, to catch
existing references to the first production.

ht

[2] http://www.w3.org/TR/REC-xml/#sec-pi
- -- 
       Henry S. Thompson, School of Informatics, University of Edinburgh
                         Half-time member of W3C Team
      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
                Fax: (44) 131 651-1426, e-mail: ht@inf.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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Received on Wednesday, 1 July 2009 17:42:45 UTC

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