Order of Declarations in DTD subsets

[Richard Light]

In message <3.0.1.16.19971222091430.52cf4bdc at pop3.demon.co.uk>, Peter
Murray-Rust <peter at ursus.demon.co.uk> writes
>Is it required that a declaration in the subset come before it is used. [I
>have tried to find this in the spec and not been able to - please forgive
>me if it's there].
>
>An example:
>
>ELEMENTs must be declared for ATTLIST in validatable documents. So is the
>following legal in this case:
>
><!ATTLIST FOO BAR CDATA #REQUIRED>
><!ELEMENT FOO ANY>

No, that's fine.  As I understand it, the general philosophy is that the
XML processor 'pauses for breath' after reading whichever DTD subsets it
is asked to read (internal only, or both).  It then sees what elements
and attribute lists have been declared.  (It is only at this point that
it can 'do the right thing' as regards (a) reporting multiple element
declarations and (b) merging, and possibly reporting on, multiple
attribute list declarations.)

>In a WF document this might have a different effect - the ATTLIST
>declaration is WF and implicitly creates an ELEMENT declaration. When this
>ELEMENT is declared, is it then an error?

No, I don't think it's helpful to see the ATTLIST declaration as
implicitly creating an ELEMENT declaration.  This isn't an error.

Richard.

Richard Light
SGML/XML and Museum Information Consultancy
richard at light.demon.co.uk

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