ITPEC IP April 2018 Question 73

More information in the same area as a linear bar code — a two-dimensional symbol stores data both horizontally and vertically.

A linear bar code holds data only in the widths of bars along one line, so it carries a few dozen characters. A two-dimensional symbol, a stacked code or a matrix code such as QR code, arranges data in two directions, so in the same area it holds far more, including text. Matrix codes also carry error-correction data, so a partly dirty or damaged symbol can still be read, and position patterns let a reader detect the orientation from any angle.

Answer (c)

Why not others:

• •(a) — a two-dimensional symbol holds data in both directions, so it is read vertically as well as horizontally, not in one direction like a linear bar code
• •(b) — two-dimensional symbols such as QR code include error-correction codes, so they can correct damaged data, not just detect errors
• •(d) — the reverse is true: finder patterns let a matrix code be read from any direction, so the scanning angle is wide

Key rule: Compared with a linear bar code, a two-dimensional code gives more data per area, reading from any angle and error correction.

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