Optical mark recognition

Optical mark recognition has been used for a long time to tabulate data provided by individual participants. It is sometimes referred to as "mark sense", but this more properly refers to Mark Sense cards which treat marked spaces similarly to punch holes to be sensed electronically, making it a form of punched card. Optical mark recognition reads marked items on a sheet directly, either by reflecting light from the sheet or passing light through the sheet.

Optical mark recognition has been used for test answer sheets, betting slips for lotteries, racetracks, and casinos, and election ballots. It was traditional to require "number 2 pencils" (the U.S. designation for standard writing pencils; the international designation is B), dating back to electronically-sensed cards which required it, but some newer sensing systems (as on election ballots) use felt-tip markers instead; in general, more modern systems are less picky about types of ink and paper used, often allowing forms to be printed on normal paper with laser or inkjet printers instead of having to be printed on special paper at a printing plant.

There is no uniform standard for the positioning of elements on these forms as they vary greatly by application, but in general there is a designated space for each option which the participants need to choose between, where they are supposed to blacken an oval, cirle, or rectangle to mark their choice. The tabulating device (often software on a PC using a sheet-fed scanner nowadays) looks for marks at particular spots depending on the design of the form used.

Optical mark regognition sheets or cards are usually human-readable as well as machine-readable, since the filled-in spaces have legends next to them indicating their purpose and meaning. In some cases, additional material may be needed to fully understand them, such as test booklets with the full questions and answers which are supplemented with optically-read answer sheets where the test-takers give their answers.