On 2/7/07, Lynn Hales <
I agree, with Ed.Just to add my two cents here.
Catalogs are probably one of the most misunderstood useful tools in the
Epic (comes from the good old days of SGML).A catalog path issue can
cause one to loose their hair (just look at me).
As I said, catalogs were an integral part of SGML, but were "deprecated"
in XML in favor of using the SYSTEM identifier.There are two identifier
types in both SGML and XML.They are the SYSTEM (the one REQUIRED by XML)
and the PUBLIC.The SYSTEM identifier provides system specific locations
for supporting files and usually has a relative or specific path to the
file.This works fine as long as you are on the desired system (or can
access it).However if one places an absolute path in SYSTEM identifier
and your system does not have that path, then you are _______ (fill in the
blank with your favorite euphonium for being caught between the rock and
The PUBLIC identifier provides a unique identifier that can be compared to
other PUBLIC identifiers in a catalog (or other simlair functioning file)
with the LOCAL SYSTEM identifier (path) as part of the catalog entry.
OASIS put out a TR a few years ago that updated the original SGML catalog
functionality.They added (and Epic supports this) the ability for a
CATALOG file to reference another CATALOG.This way you can have a master
catalog containing the paths to your DOCTYPES and then have a DOCTYPE
catalog for each DOCTYPE without having to add to your catalog path. Real
simply, in your master catalog reference the catalog path for each
doctype, the catalog is read and the appropriate catalog file is accessed.
This is very, very helpful when you consider that catalog entries are
FIFO, (First In, First Out).So (read been there done that) if you have
more than one entry for a particular catalog requirement (say DTD) in one
or more catalogs, the FIRST one encountered is read (even if it is wrong).
Read the on line help about CATALOGs.They are really a godsend when use
properly.Even the XML world is beginning to see the need for catalogs
and OASIS has an XML catalog TR.