This provides a collection of XSL files associated with Omegahat.
XSThese provide different transformations such as creating 
literate programming tools, rules for presenting Docbook-like
documents to HTML with our tags.

Several of these XSL files are considered top-level entry points that
one would pass directly to XSLT. The others are imported into these
different top-level stylesheets. In order to do this conveniently on
different machines, we must have a way to refer to the sub-XSL files
in a directory independent manner.  We can do this by explicitly
substituting the particular directory into which we install the files
later into the <xsl:import> statements. A simpler and more centralized
approach is to use catalog entries. This allows us to fix the XSL
files with references to the sub-XSL files via a URI. In the catalog,
we map this URI to a local file on the system. In this way, we only
need to change the catalog to change the location of the entire
collection.

Note that one does not have to install these files on the local
machine. Instead, one can use them implicitly from the Omegahat Web
site. This obviously requires an active network connection and can be
slow. Additionally, it will retrieve the versions available on that
site. So if there are differences, this may be important.


To use catalogs with Daniel Veillard's xsltproc, one needs
to identify the catalog file with the URI rewrites
and identifiers via the XML_CATALOG_FILES environment
variable, e.g.

  setenv XML_CATALOG_FILES file://`pwd`/catalog

One can and should use the catalog file created when this
package is configured.


To verify (or monitor) the effect of the catalog, one can set the
environment variable XML_DEBUG_CATALOG to a non-zero value, e.g. 1.



On Windows, we should not use the file:// prefix before the
local filename, but instead use the filename directly both within
the catalog and in the environment variable.
For example, 

 export XML_CATALOG_FILES=d:/cygwin/home/duncan/OmegahatXSL/catalog

and within the catalog

  <rewrite uriStartString="http://www.omegahat.org/XSL" rewritePrefix="d:/cygwin/home/duncan/OmegahatXSL/XSL/ ">
  <rewrite uriStartString="http://docbook.sourceforge.net/release/xsl/current/" rewritePrefix="d:/cygwin/home/duncan/docbook-xsl-1.65.1/">

The configuration script for this distribution of XSL files doesn't deal with Windows yet.


 