Voter-facing scanner

An electronic voting device that: accepts hand-marked or BMD-produced (Ballot Marking Device-produced) paper ballots one sheet at a time; is usually used for in-person voting; permits election workers to open and close the polls; scans a ballot and rejects it if either unreadable or un-processable; detects, interprets and validates contest selections; notifies the voter of voting exceptions (such as undervotes or overvotes) or unreadable marks; stores accepted ballots in a secure container; sorts or otherwise marks ballots or ballot images that need subsequent human review; and tabulates and reports contest results after polls are closed. This unit was previously referred to as precinct count optical scanner or PCOS.

Source: Election Terminology Glossary - Draft, National Institute of Standards and Technology (NIST), https://pages.nist.gov/ElectionGlossary/