In corporate environments, "RAR" often refers to SAP Revenue Accounting and Reporting , a solution used to comply with IFRS 15 and ASC 606 standards. If "GBT" is an internal company code (e.g., for a "Global Business Template"), would be a compressed backup of these specific financial configurations.
If the file is related to other professional fields, "RAR" could also stand for: GBT.rar
Revenue Agent Reports , detailing tax liability adjustments. In corporate environments, "RAR" often refers to SAP