Also known as Black Box Income, these are unclaimed royalties for which a publisher or writer is named but cannot be traced by a collection society. Writers who are owed royalties but cannot be found are often referred to as "lost" writers. Many US songwriters who sell their music internationally but are not signed to a publishing company with representation abroad, often become "lost" writers and lose their mechanical royalties. This income may come from the result of audits, adjustments or international sources. See Foreign Mechanicals for more.