Looking again at the explainthatstuff.com QR code up above, we have: 1  Quiet zone: An empty white border that makes it possible to isolate the code from among other printed information (for example, on a dirty envelope, among the black and white print of a newspaper, or on smudged product packaging).
Valid units must be of the length type. âºâº Definition: Centimeter. A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundreth of a metre, the current SI base unit of length. A centimetre is part of a metric system. It is the base unit in the centimetre-gram-second system of units. A corresponding unit of area is the square centimetre.
The SI unit for distance is the meter and its symbol is m. The base unit of meter can be modified by the use of prefixes. For example, centi- is a prefix meaning one one-hundredth (as in 0.01) and its symbol is c. The unit cm means centimeter and 1 cm is equal to 0.01 m.