Tim Bray <tbray@[...].com>  wrote:
| Chris Wilper wrote:
| 
|>  I'm thinking that having a URI to identify a doctype would ... be good... 
|>  Whether the format would be registered with IANA or not is another issue.
| 
| What's a doctype?  SGML had the idea that you could get to the DTD from 
| the Public or System identifier, and that's all you could get to 
| (automatically). 

I don't think SGML had that idea - at least, the text of ISO 8879 doesn't
support this notion (AFAIK).  It was, however, a popular *convention* to
treat the syntax of external subset inclusion as a purely "referential"
device.  (Strictly, a DTD is never "gotten to" - its actual specification
is in the contents of the document type declaration.)  Using an FPI for a
document type as an abstraction needs a public text class of NOTATION. 

| There was a brief wave of enthusiasm a couple of years ago from people 
| who wanted to repeat SGML's mistake of placing the schema (i.e. a bundle 
| of syntax constraints) at the center of everything, but we seem to have 
| gotten over that.

The mistake would seem to be the recurring failure to formalize a way to
*refer* to abstractions such as "document types", and to concretes such as
schemas/DTDs which are *not* syntactic components of a document instance
(as by contrast the effective contents of a document type declaration
are.)


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