The way dates are specified is the same for both backup and restore functions. The command line differs only in the use of -c for backup and -x for restore. In the case of a backup, you are asking BRU to archive files created or modified after the date you specify on the command line (see section 5, “Archiving Files: The BRU Backup Function,” “Selecting Files by Date: -n”). In the case of a restore, you are asking BRU to extract files from an existing archive based on the dates on which the files were last modified.
For the details of date specification, see section 14.