Re: [xml-dev] DTDs, W3C Schemas, RELAX NG, Schematron?

[Arjun Ray <aray@nyct.net>]

Betty Harvey <harvey@eccnet.com> wrote:
 
| Determining what schema language you should use depends upon your
| application and what you want to do.  If you need datatyping then it is
| difficult to do this with DTDs (although there are tricks).

The way I learned it, SGML leaves semantic validation to the application
level by design.  That concept seems not to have made the crossing into
XML mindspace.  

| I personally believe that DTDs still have a future. 

Yes, but not as is.  ISO standarization is both a blessing and a curse.
It brings reliability and stability, and by the same token engenders
resistance to change when the change might really be needed.  (Hmm, isn't
the next quinquennial review due soon?)

The XML initiative started about the same time as the later rounds of the
last review.  All said and done, the WebSGML TC was very receptive to the
community (say, defined as the old w3c-sgml-wg mailing list), but the XML
spec somewhat perversely missed the boat on many of the new features, and
retained a silly compatibility level with pre-WebTC SGML.  DTDs suffered a
lot from this, because XML DTDs *are* fundamentally crippled. 

(Bringing in some ideas from the TC - e.g. the DATA declared value - would
be a good start for XML DTDs.  But even SGML DTDs need more changes.)