It is most commonly known as part of voting in an election, where the scrutineer observes the counting of ballot papers, in order to check that election rules are followed.
Every ballot was inspected by a scrutineer for each candidate and then re-fed by a city staffer into the same vote counting machine as on election night.
We have robust checking procedures here involving setter, scrutineer, external examiner, and final sign off, but unfortunately even this did not prevent the mistake on this occasion.