DBT File Structure

The .DBT file is a “core dump” of three things:

• The information in SYSVOLUMES;
• The information in SYSTABLES
• The set of known filing systems used in the database. This list is maintained by operations such as the OPEN statement, which will add a filing system function name to the list after the filing system successfully completes its INSTALL operation. The list is used by the system for two main operations: FLUSH and UNLOCK ALL. When either one of these BASIC+ commands is executed, the engine sends the corresponding call to each known filing system.

The .DBT file is @rm-delimited, with volume records, followed by a blank record, followed by table records, followed by a blank record, followed by the filing system list.

The volume records are @fm-delimited, and contain seven fields:

1. The SYSVOLUMES key;
2. Field 1 of the SYSVOLUMES record;
3. Field 2 of the SYSVOLUMES record;
4. Field 3 of the SYSVOLUMES record;
5. Field 4 of the SYSVOLUMES record;
6. Blank;
7. Field 6 of the SYSVOLUMES record.

The table records are @fm-delimited, and contain five fields:

1. The SYSTABLES key;
2. Field 1 of the SYSTABLES record;
3. Field 2 of the SYSTABLES record;
4. Field 3 of the SYSTABLES record;
5. Field 4 of the SYSTABLES record;

The filing system list is @fm-delimited.