Re: ERB decisions on linking element recognition

At 16:22 24/2/97 -0800, Tim Bray wrote:

>- point out that it is not possible to duplicate external subset
>  markup declarations in the internal subset without compromising
>  SGML validity

There might be a sneaky way of overcoming this restriction.

If XML required that all ATTLISTs containing XML-LINK attributes must be
declared as parameter entities, and then invoked in the DTD as a parameter
entity reference, then the parameter entity definition could be repeated in
the external and internal subsets without upsetting an SGML system because
internal parameter entities would replace external ones. What you would end
up with, for each XML-link element would be an entry in the internal subset
of the form:

<!DOCTYPE xml-doc PUBLIC ....... [
<!ENTITY % link-type1 
'<!ATTLIST link-element1 
                   xml-link NAME #FIXED link
                   locator   CDATA #REQUIRED
                   caption   CDATA #IMPLIED ...... >'    >            
<!ENTITY % link-type2 
'<!ATTLIST link-element2 
                   xml-link NAME #FIXED xlink
                   locator   CDATA #REQUIRED
                   caption   CDATA #IMPLIED ...... >'    >         
Martin Bryan, The SGML Centre, Churchdown, Glos. GL3 2PU, UK 
Phone/Fax: +44 1452 714029   WWW home page: http://www.sgml.u-net.com/