Hello Maurice,

>I am wondering where are the system tables stored in Max OSX.

>System tables such as rdb$xxxxx.gdb

are created in each database by the CREATE DATABASE statement. They are
just normal Firebird tables. With the isql tool in its interactive shell
mode, you can list them with the command SHOW SYSTEM;

>and the security table, isc4.gdb.

Pertains to the entire server (currently), not to each database
individually. It is to be found in the root directory of your
installation. In Firebird 1.5, it is called security.fdb.

regards,
./hb