Summary: Summary: new sgml standards

[Mark Johnson <mark@phy.duke.edu>]

Hi All,

I've looked over the new proposal for structuring SGML installations
and thought I'd share what I've read.

I've collected some background material (including the proposal) here:
   
     http://dulug.duke.edu/~mark/debian/sgml/


The proposed changes are substantial, and will likely make packaging
easier. They also allow for multiple versions of some packages to be
installed.


Here's a quick summary:


 A. /usr/lib/sgml/ --> /usr/share/sgml/
   -----------------------------------

  The architecture independent stuff now goes in /usr/share/sgml/


 B. Directory Layout of /usr/share/sgml/
   ------------------------------------

   (i.) Top-level directories are based on classes of related schema
        (dtds) and their schema-specific components - stylesheets,
        entites, etc. Like this:

	/usr/share/sgml/
			docbook/
			debiandoc/
			html/
		
   (iii.) The docbook sub-directories are package-oriented:

       /usr/share/sgml/docbook/
				sgml-dtd-3.1/
				sgml-dtd-4.1/
				xml-dtd-4.1/
				dsssl-stylesheets-1.57/
				xsl-stylesheets-1.24/
				gnome-customization-0.1/


   (ii.) General things that everybody uses get their own top-level
         directory, complete with version numbers:

	 /usr/share/sgml/
			sgml-iso-entities-8879.1986/
			xml-iso-entities-8879.1986/
			jade-1.2.1/
			openjade-1.3/



 C. Catalog Handling
   ----------------

    *System Catalogs Only Point to Package Catalogs*
    

     Three kinds of catalogs:

    1  Package Catalogs  - package-specific
			 - all named "catalog"
			
	Examples: 

	/usr/share/sgml/docbook/xsl-dtd-4.0/catalog
	/usr/share/sgml/docbook/dsssl-stylesheets-1.54/catalog



    2  Centralized Catalogs  - reside in /etc/sgml/ 
			     - are dtd-specific
			     - can be version-numbered
			     - end in .cat
			     - point to Package Catalogs via
			       CATALOG or DELEGATE keywords

	Example:
		/etc/sgml/
			  sgml-docbook.cat
			  sgml-docbook-3.1.cat
			  sgml-docbook-4.1.cat
			  xml-docbook-4.1.cat
	 

	Example Contents:
	
	 -- sample contents of /etc/sgml/foo-1.05.cat --
	 CATALOG /usr/share/sgml/foo/xml-dtd-1.05/catalog
	 CATALOG /usr/share/sgml/foo/xsl-stylesheets-0.1/catalog


    3  The Super Catalog - named /etc/sgml/catalog
			 - points to Centralized Catalogs only
			 
	Example Contents:

		   -- sample contents of /etc/sgml/catalog --
		     CATALOG /etc/sgml/sgml-docbook.cat
		     CATALOG /etc/sgml/xhtml.cat
		     CATALOG /etc/sgml/mathml.cat

	--- End Quick Summary --


There are many more details, but that's the general idea. 

One question comes to mind:

    How to handle relative paths for stylesheets that are
    customizations of a "main" distribution?

    E.g. The website xsl stylesheets call files that are part of the
	 full docbook xsl stylesheet set, and need to find the
	 docbook.xsl via a generic path like 
		     ../xsl-stylesheets/html/docbook.xsl
	 
	 One solution would be to put an "xsl-stylsheets" entry in 
	 /etc/alternatives that /usr/share/docbook/xsl-stylesheets 
	 points to. 


Hopefully this info will alleviate some of the confusion. Ardo plans
to have a policy draft ready sometime in January. We could help move
things along by addressing issues as we see them now.

Cheers,
Mark