Draft Spec mark 2
ericz at ENTO.CSIRO.AU
Wed Sep 6 11:56:18 CEST 2000
At 09:40 6/09/2000 +1100, Greg Whitbread wrote:
>Mixed content might also impact some of the validation
>and context issues discussed earlier.
> From http://www.w3.org/TR/1998/REC-xml-19980210 ,
> Extensible Markup Language (XML) 1.0.
> "An element type has mixed content when elements of that type may contain
> character data, optionally interspersed with child elements. In this case,
> the types of the child elements may be constrained, but not their order or
> their number of occurrences:"
While validation of mixed content is indeed a problem when using XML 1.0
DTDs, XML Schema can handle it. Quoting from
http://www.w3.org/TR/xmlschema-0/ , XML Schema Part 0: Primer (W3C Working
Draft, 7 April 2000)
"Note that the mixed model in XML Schema differs fundamentally from the mixed
model in XML 1.0. Under the XML Schema mixed model, the order and number of
child elements appearing in an instance must agree with the order and number
of child elements specified in the model. In contrast, under the XML 1.0
mixed model, the order and number of child elements appearing in an instance
cannot be constrained. In sum, XML Schema provides full schema validation of
mixed models in contrast to the partial schema validation provided by XML
While mixed content is best avoided, I'd hate to rule it out completely. In
particular, it might be good if those elements or attributes containing
blobs of text could also contain some embedded HTML (or, rather, XHTML)
markup, to allow for italics, sub- and super-scripts and so on.
CSIRO Division of Entomology
E-mail: ericz at ento.csiro.au
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