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<TITLE>SP - Catalogs</TITLE>
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<H1>Catalogs</H1>
<P>
The entity manager generates a system identifier for every external
entity using catalog entry files in the format defined by <A
HREF="http://www.sgmlopen.org/sgml/docs/library/9401.htm">SGML Open
Technical Resolution TR9401:1995</A>. The entity manager will give an
error if it is unable to generate a system identifier for an external
entity. Normally if the external identifier for an entity includes a
system identifier then the entity manager will use that as the
effective system identifier for the entity; this behaviour can be
changed using <CODE>OVERRIDE</CODE> or <CODE>SYSTEM</CODE> entries in
a catalog entry file.
<P>
A catalog entry file contains a sequence of entries in one of the
following forms:
<DL>
<DT>
<SAMP>PUBLIC <VAR>pubid</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <SAMP><VAR>sysid</VAR></SAMP> should be used as
the effective system identifier if the public identifier is
<SAMP><VAR>pubid</VAR></SAMP>. <SAMP><VAR>Sysid</VAR></SAMP> is a
system identifier as defined in ISO 8879 and
<SAMP><VAR>pubid</VAR></SAMP> is a public identifier as defined in ISO
8879.
<DT>
<SAMP>ENTITY <VAR>name</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <VAR>sysid</VAR> should be used as the effective
system identifier if the entity is a general entity whose name is
<VAR>name</VAR>.
<DT>
<SAMP>ENTITY %<VAR>name</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <SAMP><VAR>sysid</VAR></SAMP> should be used as
the effective system identifier if the entity is a parameter entity
whose name is <VAR>name</VAR>. Note that there is no space between
the <SAMP>%</SAMP> and the <SAMP><VAR>name</VAR></SAMP>.
<DT>
<SAMP>DOCTYPE <VAR>name</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <SAMP><VAR>sysid</VAR></SAMP> should be used as
the effective system identifier if the entity is an entity declared in
a document type declaration whose document type name is <VAR>name</VAR>.
<DT>
<SAMP>LINKTYPE <VAR>name</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <SAMP><VAR>sysid</VAR></SAMP> should be used as the
effective system identifier if the entity is an entity declared in a
link type declaration whose link type name is <VAR>name</VAR>.
<DT>
<SAMP>NOTATION <VAR>name</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <SAMP><VAR>sysid</VAR></SAMP> should be used as
the effective system identifier for a notation whose name is
<SAMP><VAR>name</VAR></SAMP>. This is an extension to the SGML Open
format. This is relevant only with the <SAMP>-n</SAMP> option.
<DT>
<SAMP>OVERRIDE <VAR>bool</VAR></SAMP>
<DD>
<SAMP><VAR>bool</VAR></SAMP> may be <SAMP>YES</SAMP> or
<SAMP>NO</SAMP>. This sets the overriding mode for entries up to the
next occurrence of OVERRIDE or the end of the catalog entry file. At
the beginning of a catalog entry file the overriding mode will be NO.
A PUBLIC, ENTITY, DOCTYPE, LINKTYPE or NOTATION entry with an
overriding mode of YES will be used whether or not the external
identifier has an explicit system identifier; those with an overriding
mode of NO will be ignored if external identifier has an explicit
system identifier. This is an extension to the SGML Open format.
<DT>
<SAMP>SYSTEM <VAR>sysid1</VAR> <VAR>sysid2</VAR></SAMP>
<DD>
This specifies that <VAR>sysid2</VAR> should be used as the effective
system identifier if the system identifier specified in the external
identifier was <SAMP><VAR>sysid1</VAR></SAMP>. This is an extension
to the SGML Open format. <VAR>sysid2</VAR> should always be quoted to
ensure that it is not misinterpreted when parsed by a system that does
not support this extension.
<DT>
<A NAME="sgmldecl"><SAMP>SGMLDECL <VAR>sysid</VAR></SAMP></A>
<DD>
This specifies that if the document does not contain an SGML declaration,
the SGML declaration in <SAMP><VAR>sysid</VAR></SAMP> should be implied.
<DT>
<SAMP>DOCUMENT <VAR>sysid</VAR></SAMP>
<DD>
This specifies that the document entity is <SAMP><VAR>sysid</VAR></SAMP>.
This entry is used only with the <SAMP>-C</SAMP> option.
<DT>
<SAMP>CATALOG <VAR>sysid</VAR></SAMP>
<DD>
This specifies that <SAMP><VAR>sysid</VAR></SAMP> is the system
identifier of an additional catalog entry file to be read after this
one. Multiple <SAMP>CATALOG</SAMP> entries are allowed and will be
read in order. This is an extension to the SGML Open format.
<DT>
<SAMP>BASE <VAR>sysid</VAR></SAMP>
<DD>
This specifies that relative storage object identifiers in system
identifiers in the catalog entry file following this entry should be
resolved using first storage object identifier in
<SAMP><VAR>sysid</VAR></SAMP> as the base, instead of the storage
object identifiers of the storage objects comprising the catalog entry
file. This is an extension to the SGML Open format. This extension
is proposed in <A HREF=
SGML Open Catalogs and MIME to Exchange SGML Documents</A>.
Note that the <CODE><VAR>sysid</VAR></CODE> must exist.
<DT>
<SAMP>DELEGATE <VAR>pubid-prefix</VAR> <VAR>sysid</VAR></SAMP>
<DD>
This specifies that entities with a public identifier that has
<SAMP><VAR>pubid-prefix</VAR></SAMP> as a prefix should be resolved
using a catalog whose system identfier is
<SAMP><VAR>sysid</VAR></SAMP>. For more details, see <A
HREF="http://www.entmp.org/fpi-urn/delegate.html">A Proposal for
Delegating SGML Open Catalogs</A>. This is an extension to the SGML
Open format.
</DL>
<P>
The delimiters can be omitted from the <SAMP><VAR>sysid</VAR></SAMP>
provided it does not contain any white space. Comments are allowed
between parameters delimited by <SAMP>--</SAMP> as in SGML.
<P>
The environment variable <SAMP>SGML_CATALOG_FILES</SAMP> contains a
list of catalog entry files. The list is separated by colons under
Unix and by semi-colons under MS-DOS and Windows.. These will be
searched after any catalog entry files specified using the
<SAMP>-m</SAMP> option, and after the catalog entry file called
<SAMP>catalog</SAMP> in the same place as the document entity. If
this environment variable is not set, then a system dependent list of
catalog entry files will be used. In fact catalog entry files are not
restricted to being files: the name of a catalog entry file is
interpreted as a system identifier.
<P>
A match in one catalog entry file will take precedence over any match
in a later catalog entry file. A more specific matching entry in one
catalog entry file will take priority over a less specific matching
entry in the same catalog entry file. For this purpose, the order of
specificity is (most specific first):
<UL>
<LI>
<SAMP>SYSTEM</SAMP> entries;
<LI>
<SAMP>PUBLIC</SAMP> entries;
<LI>
<SAMP>DELEGATE</SAMP> entries ordered by the length of the prefix,
longest first;
<LI>
<SAMP>ENTITY</SAMP>, <SAMP>DOCTYPE</SAMP>, <SAMP>LINKTYPE</SAMP> and
<SAMP>NOTATION</SAMP> entries.
</UL>
<P>
<ADDRESS>
James Clark<BR>
jjc@jclark.com
</ADDRESS>
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