Catalogs

The entity manager generates a system identifier for every external entity using catalog entry files in the format defined by SGML Open Technical Resolution TR9401:1997. 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 OVERRIDE or SYSTEM entries in a catalog entry file.

A catalog entry file contains a sequence of entries in one of the following forms:

PUBLIC pubid sysid

This specifies that sysid should be used as the effective system identifier if the public identifier is pubid. Sysid is a system identifier as defined in ISO 8879 and pubid is a public identifier as defined in ISO 8879.

ENTITY name sysid

This specifies that sysid should be used as the effective system identifier if the entity is a general entity whose name is name.

ENTITY %name sysid

This specifies that sysid should be used as the effective system identifier if the entity is a parameter entity whose name is name. Note that there is no space between the % and the name.

DOCTYPE name sysid

This specifies that sysid 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 name.

LINKTYPE name sysid

This specifies that sysid 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 name.

NOTATION name sysid

This specifies that sysid should be used as the effective system identifier for a notation whose name is name. This is relevant only with the -n option.

OVERRIDE bool

bool may be YES or NO. 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.

SYSTEM sysid1 sysid2

This specifies that sysid2 should be used as the effective system identifier if the system identifier specified in the external identifier was sysid1. sysid2 should always be quoted to ensure that it is not misinterpreted when parsed by a system that does not support this extension.

SGMLDECL sysid

This specifies that if the document does not contain an SGML declaration, the SGML declaration in sysid should be implied.

DTDDECL pubid sysid

This specifies that if the document does not contain an SGML declaration and uses a doctype declaration with public identifier pubid, the SGML declaration in sysid should be implied.

DOCUMENT sysid

This specifies that the document entity is sysid. This entry is used only with the -C option.

CATALOG sysid

This specifies that sysid is the system identifier of an additional catalog entry file to be read after this one. Multiple CATALOG entries are allowed and will be read in order.

BASE sysid

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 sysid as the base, instead of the storage object identifiers of the storage objects comprising the catalog entry file. Note that the sysid must exist.

DELEGATE pubid-prefix sysid

This specifies that entities with a public identifier that has pubid-prefix as a prefix should be resolved using a catalog whose system identfier is sysid. For more details, see A Proposal for Delegating SGML Open Catalogs.

SGML name sysid

This specifies that the SGML declaration body in sysid should be used when the document starts with a reference to an SGML declaration named name. This is an OpenSP-specific extension of the SGML Open catalog format. SGML declaration references are defined in Annex K of ISO 8879.

The delimiters can be omitted from the sysid provided it does not contain any white space. Comments are allowed between parameters delimited by -- as in SGML.

The entity manager will look for catalog entry files as follows:

1. a file called catalog in the same directory as the document entity, unless the environment variable SP_USE_DOCUMENT_CATALOG has the value NO or 0;
2. any catalog entry files specified using the -c option;
3. a list of files specified by the environment variable SGML_CATALOG_FILES; the list is separated by colons under Unix and by semi-colons under MS-DOS and Windows; 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.

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):

• SYSTEM entries;
• PUBLIC entries;
• DELEGATE entries ordered by the length of the prefix, longest first;
• ENTITY, DOCTYPE, LINKTYPE, NOTATION and SGML entries.

For the purpose of implying an SGML declaration, DTDDECL entries are more specific than SGMLDECL entries.