Allows definition of a catalog which shares most of the characteristics of another catalog. Only the directives that are changed from the base catalog are added. The parameters are 1) the catalog ID 2) the base catalog ID, 3) the directory to use (typically the same as the base catalog), and 4) the SCRIPT_NAME that will trigger the catalog. Any additional parameters are aliases for the SCRIPT_NAME.
The main reason that this would be used would be to conserve memory in a series of stores that share most of the same pages or databases.
SubCatalog sample2 sample /usr/catalogs/sample /cgi-bin/sample2