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Re: Why are erroneous ENTITY declarations not caught in XML va

• From: ht@inf.ed.ac.uk (Henry S. Thompson)
• To: Michael Kay <mike@saxonica.com>
• Date: Tue, 23 Oct 2012 18:42:14 +0100

Michael Kay writes:

> On 23/10/2012 15:22, Henry S. Thompson wrote:
>> Read the spec [1], guys:
>>
>>    4.4.7 Bypassed
>>
>>      When a general entity reference appears in the EntityValue in an
>>      entity declaration, it must be bypassed and left as is.
>>
>> ht
>>
>> [1] http://www.w3.org/TR/REC-xml/#bypass
>
> But a reasonable reader could assume that before bypassing the entity
> reference, you need to identify it and check that it is well-formed,
> which implies checking WFC: Entity Declared.
>
> Presumably you're supposed to check that the name is a valid
> name. Does the grammar rule saying the name must be valid have a
> different status from the extra-grammatical rule saying it must
> resolve?

I don't agree with your analysis.  The spec. gives more indication of
what 'bypass' means in section 4.6 [2]:

  The actual replacement text that is included (or included in
  literal) as described above must contain the replacement text of any
  parameter entities referred to, and must contain the character
  referred to, in place of any character references in the literal
  entity value; however, general-entity references must be left as-is,
  unexpanded.

I think the dead hand of SGML is visible here, just as it is in saying
that 

 <!DOCTYPE foo [
 <!ELEMENT foo (a,b?)>
 <!ELEMENT a EMPTY>
 ]>
 <foo><a/></foo>

is valid.  The general 'principle' is "Undefined things that aren't
used aren't errors".

I agree that the priority of this statement over WFC: Entity Declared
needs to be clarified.  The existing text [3], which says

  the Name given in the entity reference must match that in an entity
  declaration that does not occur within the external subset or a
  parameter entity,

should be modified to include "or within a *literal entity value*". . .

ht

[2] http://www.w3.org/TR/REC-xml/#intern-replacement
[3] http://www.w3.org/TR/REC-xml/#wf-entdeclared
-- 
       Henry S. Thompson, School of Informatics, University of Edinburgh
      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
                Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                       URL: http://www.ltg.ed.ac.uk/~ht/
 [mail from me _always_ has a .sig like this -- mail without it is forged spam]

• References:
  • Why are erroneous ENTITY declarations not caught in XML validation?
    • From: "Costello, Roger L." <costello@mitre.org>
  • Re: Why are erroneous ENTITY declarations not caught inXML validation?
    • From: David Carlisle <davidc@nag.co.uk>
  • Re: Why are erroneous ENTITY declarations not caught inXML validation?
    • From: David Carlisle <davidc@nag.co.uk>
  • Re: Why are erroneous ENTITY declarations not caught in XML validation?
    • From: ht@inf.ed.ac.uk (Henry S. Thompson)
  • Re: Why are erroneous ENTITY declarations not caught inXML validation?
    • From: Michael Kay <mike@saxonica.com>