Parameter entities for DTD modularity (was: Re: Multiple docs in 'wrapper')

Liam R. E. Quin liamquin at
Sun Oct 31 07:26:50 GMT 1999

On Sun, 31 Oct 1999, John Tigue wrote:
> Another alternative could be implemented now based solely on  
> XML 1.0. Consider using external parameter entity references. 

During the XML design phase, I felt that the SYSTEM (and PUBLIC
identifiers in the document type declaration should have
been dispened with, 

<!DOCTYPE Sock SYSTEM "hosiery.dtd" [
    <!ENTITY myName "Lam">

is more or less the same (in XML, not SGML) as

<!DOCTYPE Sock [
    <!ENTITY myName "Lam">

    <!ENTITY % theDTD STYSTEM "hosiery.dtd">

The extra syntax in the 2nd example is outweighed by the
fact you'd probably need inclusions anyway, and having just
one syntax is simpler.  Furthermore, the first example is
confusing: "hosiery.dtd" gets included *after* the
declaration of myName in both cases, but you'd think this not to
be the case in the first example, unless you had read the spec.

The main advantage would be that people would be more familiar
with how to include DTD fragments in XML!  Most people learn the
DOCTYPE/STSTEM method, ad fewer learn the external parameter
entity reference.

It's too late to remove the featur now, but people writing tutorials
and books and examples for XML would do well to consider introducing
the second before the first, I think.


Liam Quin, Barefoot Computing, Toronto;  The barefoot agitator
l i a m q u i n     at    i n t e r l o g    dot   c o m
Ankh on

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