qr – generate QR code
The QR standard defines different sizes labelled version 1 to version 40.
By default the smallest possible is chosen automatically.
By default bytes are encoded directly with no translation.
Coding efficiency can be increased by reducing the set of legitimate characters using the
International Standard ISO/IEC 18004.
The standard specifies the use of JIS-8 encoding in the default mode, however rumour has it that readers recognize UTF-8.
The more advanced coding features (Kanji mode, extended modes, switching modes midstream) are not supported.