When you restore with external backup tools, the Database Manager identifies the backup to be restored using the External Backup IDs.

• You can determine and display the information about the backups known to the backup tool, and in particular about the external backup IDs, using the Database Manager GUI:
  Database Manager GUI: SAP DB 7.4, Display Backup History section.
• The information about the backups known to the backup tool, and in particular the external backup IDs, are displayed by the DBMGUI during a restore.
  Database Manager GUI: SAP DB 7.4, sections Restoring the Last Complete Data Backup / Restoring a Backup from the Backup History / Restoring Without a Backup History