The system catalog forms the core of your database. It comprises a set of system tables that describe all of the tables and relations described by the database. You can have multiple system catalogs (databases), but only a single catalog may be accessed at one time. The system catalog is portable between machines with the same byte ordering (little endian to little endian and big endian to big endian).

AcuXDBC creates a system catalog corresponding to information it reads from your XFDs. Once this information is loaded,AcuXDBC no longer requires your XFDs. Instead, it refers to the system catalog to obtain the information needed to construct and display your COBOL tables. This gives you the option of providing end users with XFD files for building their own system catalog, or you can provide them with a pre-built system catalog. The ability to supply a pre-built system catalog can lead to other benefits for your applications. For example, you can also pre-build user logins, database object permissions, and complex data handling views.

The primary advantage to a system catalog is that it allows for much greater relational-database-like behavior.

This help section describes the structure of the system catalog, and in doing so, orients you to the environment from which you can access and manage your database. It shows how a newly created COBOL database may appear to users after the initial install of AcuXDBC and a system catalog populated with sample customer data. Database administrators and other programmers should find this information useful for more effectively managing and querying the database.

Note: This section is not intended to teach SQL programming or how to manage a database. Consult a resource dedicated to SQL programming and database management for a fundamental understanding of these concepts.