====== 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|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|FLUSH]] and [[unlock|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:

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

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

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

The filing system list is @fm-delimited.