Mixed content considered harmful...

John Cowan cowan at locke.ccil.org
Tue May 11 20:32:48 BST 1999


Paul Prescod wrote:

> #PCDATA is just a data type that is unconstrained. You should be able to
> mix data type refs, #PCDATA and element type refs in content models with
> impunity (barring real parsing ambiguity). Using old syntax:
> 
> <!ELEMENT SECTION (#PCDATA, P+)>
> <!ELEMENT FIG (#PCDATA|IMG)>
> <!ELEMENT HTML (TITLE,(#PCDATA|P)+)>

I need to be convinced of this.

Can you sketch an algorithm that will convert SGML-style (or &-less
SGML-style) content models involving #PCDATA into content models
involving #PCDATA and #WS, where #WS is a data type that matches
only white space, such that random white space around tags will be properly
accounted for?

Remember that XML parsers are required to pass along all whitespace,
(i.e. it all appears in the infoset, barring whitespace outside the
root element), so it needs to be accounted for somehow, when it is
#PCDATA and when it isn't.

-- 
John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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