This function returns the storage object identifier (path name) for the public identifier pubid specified on the first SGMLDECL or DTDDECL keyword found in a catalog file.

The catalogpath argument specifies a list of directories to search for the catalog file. If it is not specified, the path list specified in the catalogpath set option, which is initialized from the environment variable APTCATPATH, is searched.

The function returns a null string if neither a SGMLDECL nor a DTDDECL keyword specifying pubid is found in any of the catalogs searched.