RE: Doctypes, Declarations, and HTML Versions

On Tue, 5 Oct 1999 JOrendorff@ixl.com wrote:

> To create a class of documents, you need to specify
> (a) the syntactic rules for instance documents and
> (b) the semantic meanings of the tags you will use.

Sort of true.  You need to provide these things, but you don't need to
provide them for all elements, only those that you care about.  Therefore
c, and d below are no more of a problem then they are normally.
 
> These rules will probably evolve.  There will also be
> exceptions where you'll want to incorporate other data
> objects.  So you'll also want
> (c) some sort of versioning and
> (d) extensibility.
> 
> SGML DTDs provide (a).  I think "XML Schema: Structures"
> aims to provide (a) (b) and (d). 

A DTD would provide (a), but DTD's are not completely specifed in SGML. 
Only a document type delcaration is given.  Here the words `document type'
are misleading.

So nothing in SGML provides any of this.  Architectures provide (a) and
(b).  As noted above (c) and (d) are not really a problem if (a) is done
correctly.

-- 
Russell O'Connor                           roconnor@uwaterloo.ca
       <http://www.undergrad.math.uwaterloo.ca/~roconnor/>
``And truth irreversibly destroys the meaning of its own message''
-- Anindita Dutta, ``The Paradox of Truth, the Truth of Entropy''

Received on Tuesday, 5 October 1999 17:44:42 UTC