A QR code uses error correction encoding and mask patterns. The QR code's size is represented by a number, called a version number. To ensure that a QR code scanner accurately decodes what it scans, the QR code specification requires that each code include a format information string, which tells the QR code scanner which error correction level and mask pattern the QR code is using. In addition, for version 7 and larger, the QR code specification requires that each code include a version information string, which tells the QR code scanner which version the code is.