An electronic voting device that:
accepts stacks of hand-marked or Ballot Marking Device (BMD)-produced paper ballots and automatically processes them until the stack is empty;
is usually used at an election jurisdiction’s central location;
is mostly commonly used to process absentee ballots;
usually has input and output hoppers for ballots; scans a ballot and rejects it if either unreadable or un-processable;
detects, interprets, and validates contest selections;
detects and sorts (either digitally or physically) ballots that are unreadable or un-processable, or that contain undeterminable selections, marking exceptions, or write-ins;
and tabulates and reports contest results as required.
This unit was previously referred to as central count optical scanner or CCOS.
Source: Election Terminology Glossary - Draft, National Institute of Standards and Technology (NIST), https://pages.nist.gov/ElectionGlossary/