Between raw and cooked II: Are? DTDs are just for validation

roddey at roddey at
Fri Apr 2 20:56:25 BST 1999

>>David Megginson wrote:
>>There *is* a potentially nasty problem lurking here: the DTD may
>>contain default values for attributes as well as validation
> If DTDs *were* only for validation there would be no issue here. However
>DTDs provide additional functionality beyond validation, namely default
>attributes and entities. The problem exists in that XML parsers can
>whether or not to validate and in so doing the <em>information
>of the XML document is altered.
> Validation is optional. Says so. Given this, the question becomes: ought
>parsers be allowed to expand entities and default attributes with
>turned off? What problem does this create?

Personally I think that the only thing that makes sense for the vast
majority of situations is that the DTD is parsed if present and its
(non-structural content) information is used, regardless of whether actual
validation is done. Validation should be requested separately from the
presence of the DTD, because of the DTD's overloaded use.

This is the way the new IBM parsers work, and I think its the correct thing
to do. Anything less than that should also be something that is
specifically requested because otherwise it would probably just confuse the

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