The British sort code is only used for domestic money transfers.
It consists of a four character header comprising an ISO 3166-1 alpha-2 country code, followed by two check digits that are calculated using a mod-97 technique and a country-specific Basic Bank Account Number (BBAN) of up to thirty alphanumeric characters.
Every company that does financial transactions can benefit from having a SORT Codes database to verify it's payments, minimizing the risk of mistyped or incorrect data.
The suffix is automatically allocated by Voca, and are numbered in sequence starting with 01 for the first subbranch. Those countries which use International Bank Account Numbers (IBAN) have mostly integrated the bank code into the prefix of specifying IBAN account numbers.
It identifies both the bank, and the branch where the account is held.