alternate record key
In database and file systems, a secondary key used for indexing or accessing records in a different order from the primary key.
このデータベースでは、副レコードキーを使って高速に検索できる。
In this database, you can search quickly using an alternate record key.
Compound of 副 (ふく, 'secondary, auxiliary') and レコードキー ('record key'), a loanword from English.