> What's the purpose of an empty AttlistDecl?
> Shouldn't production [52] read instead as follows?
>
> AttlistDecl ::= '<!ATTLIST' S Name AttDef+ S? '>'
>
> (+ instead of *)
Actually, it turns out to be remarkably useful for external DTD
subsets. Consider this:
<![%security;[
<!ENTITY % security-atts "
level CDATA #REQUIRED
auth CDATA #REQUIRED">
]]>
<!ENTITY % security-atts "">
<!ATTLIST section %security-atts;>
Now, if the %security; parameter entity is set to "INCLUDE" (to enable
security features), you will get
<!ATTLIST section
level CDATA #REQUIRED
auth CDATA #REQUIRED>
If the %security; parameter entity is set to "IGNORE" (to disable
security features), you will get
<!ATTLIST section>
Fortunately, this is still legal in XML.
All the best,
David
--
David Megginson ak117@freenet.carleton.ca
Microstar Software Ltd. dmeggins@microstar.com
http://home.sprynet.com/sprynet/dmeggins/
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