Re: questions about element declarations

At 06:35 AM 24/9/96 +0100, W. Eliot Kimber wrote:

>>* Should XML prohibit the use of inclusion and exclusion exceptions in
>>element declarations? (11.2.4, 11.2.5)?
>Yes.  Exclusions are, with very rare exceptions, a bad thing, causing much
>more trouble than they're worth. Inclusions, while expressing a useful
>semantic, also cause more trouble then they're worth and require DTD

Exclusions are very useful for prohibiting nesting of objects in OR groups
that are shared, such as those typically found in  %text; parameter entites.
For example:

<!ENTITY % text   (#PCDATA|a|b|c)>

<!ELEMENT p (%text;)>
<!ELEMENT a (%text;) -(a)>

I cannot agree that they are "a bad thing">
Martin Bryan, The SGML Centre, Churchdown, Glos. GL3 2PU, UK 
Phone/Fax: +44 1452 714029   WWW home page: http://www.u-net.com/~sgml/