text: For consistency with the format of other UK addresses, in 2012 BFPO and Royal Mail jointly introduced an optional alternative postcode format for BFPO addresses, using the new non-geographic postcode area "BF" and the notional post town "BFPO". Each BFPO number is assigned to a postcode in the standard UK format, beginning "BF1".  Inward codes are assigned: 0 – Germany, 1 – UK, 2 – Rest of Europe, 3 – Rest of World, 4 – Ships and Naval Parties, 5 – Rest of World, Operations and Exercises, 6 – Rest of World, Operations and Exercises. The database was released commercially in March 2012 as part of the Royal Mail Postal Address File (PAF). A postcode is not required if the traditional "BFPO nnnn" format is used.
  Non-geographic codes
  Most postcodes apply to a geographic area but some are used only for routing and cannot be used for navigation or estimating distances. They are often used for direct marketing and PO boxes (e.g. in the Brighton BN postcode area, BN50-BN52 are allocated to PO Boxes in Brighton, Rottingdean and Hove). Non-geographic postcode area BX (possibly for "PO Box"?) is entirely non-geographic, with all its codes independent of the location of the recipient. They are also referred to as "business service indicator addresses", which are used for centralised scanning of inward mail.Similarly, the XX postcode area is allocated for parcel returns of large volume retailers (and for medical sample testing during the COVID pandemic).