[xml] PEReferences - tricky and error-prone

Dear All,

While trying to eliminate the last usage of ctxt->token, I had to do
some experiments with PERefences. As already the W3C REC points
out, PERefeferences are primary used to author tricky and
error-prone XML, and so I'm somewhat confused. 

Is the following is valid (current libxml2 votes no, as 
does XMLSpy 3.5):

<?xml version='1.0'?>
<!DOCTYPE root SYSTEM 't4.dtd'>

<!ENTITY % percent "&#x25;">
<!ENTITY %percent; def "ghi">
<!ENTITY abc "%def;">

This example tests, whether it is O.K. to have the
'%' of an EntitityDecl given by an PEReference.

It is stated in the REC section 2.8
The markup declarations may be made up in whole or in part of 
the replacement text of parameter entities. The productions later 
in this specification for individual nonterminals (elementdecl,
AttlistDecl, and so on) describe the declarations after all the 
parameter entities have been included.

Parameter entity references are recognized anywhere in the 
DTD (internal and external subsets and external parameter entities),
except in literals, processing instructions, comments, and the
contents of ignored conditional sections (see 3.4 Conditional
 Sections). They are also recognized in entity value literals. The use 
of parameter entities in the internal subset is restricted as described

So my reading of these two paragraphs imply, that the '%'
may be read from an PEReference.


Peter Jacobi

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