Catalog Policy comments

[Jor-el <jorel@austin.rr.com>]

Mark,

	Here are a couple of queries / comments :

1.  I'm not clear as to why we need both package and local catalogs. It
seems to me that this is an extra level of gratuitous indirection. Quoting
from your draft 2 :

<quote>
  Package Catalogs (/etc/xml/$package.xcat)
  ------------
   Purpose:

   The primary roles of the Package Catalogs are 

     a. to delegate entity searches to the appropriate Local Catalogs
        (/usr/share/xml/$dtd-dir/catalog.xml), based on FPI and SYSID fragments, 

     b. to rewrite SYSTEM identifier prefixes so that, say, web-based urls are
        mapped to local filenames, and

     c. to define and map abbreviations for often-used stylesheet files to
        filenames on the local filesystem. (e.g. db-chunk.xsl)
</quote>

	...from draft 3 :

<quote>

  Local Catalogs (/usr/share/xml/DTD-DIR/catalog.xml)
  --------------
   Purpose:

   The primary role of the Local Catalogs is 

     a. to map PUBLIC and SYSTEM identifiers to local filenames
</quote>

	It is quite evident that when (a) and (b) are executed by package
catalogs, it is quite possible to specify the target filename in full thus
eliminating the need for parsing a third catalog in these two cases. (c),
if I read it write, actually maps to a filename directly, and so wouldnt
have a corresponding entry in the local catalog. If there is a benefit to
having local and package catalogs, please enlighten me.

2.  From draft 1 where you state the goals of ther root catalog :

         - Allow for designation of xsl stylesheet shortcuts, e.g. the
           capability to provide "db-chunk.xsl" as input to an XSLT processor,
           rather than having to type
           "/usr/share/xml/docbook/stylesheets/nwalsh/html/chunk.xsl"

	(a) I've never tried this, so I wouldnt know - does this actually
	work? One would think that a relative reference like that would be
	resolved by the XSL processor relative to the file containing the 
	reference.

	(b) What about namespace collisions? Since, we are allowing
	references in a global namespace by this mechanisms, how do we
	handle multiple files with the same names? Special prefixes? Do we
	need to register these prefixes so that different packages dont
	argue over the "cool" prefixes?

3.  Nit-picking : your draft 1 specifies the name of the root catalog as
/etc/xml/xcatalog . I dont believe we have a choice in this as most tools
assume /etc/xml/catalog . Also, I had proposed the .xcat filename
extension for catalog files (which you use for package catalogs) to which
Adam had objected stating that since they are XML files, it would be
better to have them with the .xml extension.

	Otherwise, I think you have a great job documenting and clarifying
things. I greatly appreciate the time and effort you have put into this.

Regards,
Jor-el