Proposal for src files

W. Eliot Kimber eliot at
Wed Apr 1 20:23:48 BST 1998

At 09:22 AM 4/1/98, Peter Murray-Rust wrote:
>Is it possible to combine these two so that we express a DTD in a standard
>XML notation? 

Technical note: at the recent NCITS (nee ANSI) meeting, the U.S. delegation
to WG4 developed a proposed ammendment to the SGML standard that codifies
the idea of DOCTYPE declaration components that are not in DTD syntax.

The idea is very simple: allow "parameter data entities", e.g.:

<!NOTATION MySchemaLanguage 
  PUBLIC "-//ME//NOTATION My Schema Language//EN" 
<!ENTITY % my-declarations 
  SYSTEM "mydecl.schema" 
  NDATA MySchemaLanguage 

The only requirement is that the document allow omitted DTD declarations.
If the parser understands the notation of the parameter data entity, it can
use it to do SGML validation to the degree it can construct the prolog
portion of the document grove from the entity. If it doesn't understand the
notation then the normal implied declaration rules apply.  Any validation
services over and above SGML validation must be clearly labeled as such
(i.e., consistent with SGML's current distinction between validation errors
and application warnings).

Because the external DTD subset is really a parameter entity, you can make
the whole external subset a parameter data entity:

<!DOCTYPE MyDoc SYSTEM "myschema.schema" NDATA MySchemaLanguage [
  <!NOTATION MySchemaLanguage 
    PUBLIC "-//ME//NOTATION My Schema Language//EN"  

Note that the internal subset is unchanged: you must use normal DTD syntax
within the DTD subset.

If approved by ISO, this ammendment would make SGML's official policy on
schemas "use any syntax you want, we don't care". In particular, we have no
plans or desire to define alternative syntaxes for DTD representation
within ISO 8879.  This does not, of course, preclude separate schema
standardization efforts within NCITS or ISO (or anywhere else).

So far this proposal seems to be non-controversial. 

<Address HyTime=bibloc>
W. Eliot Kimber, Senior Consulting SGML Engineer
Highland Consulting, a division of ISOGEN International Corp.
2200 N. Lamar St., Suite 230, Dallas, TX 95202.  214.953.0004

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