ISO/IEC 18004
ISO/IEC 18004 is the international standard defining QR code symbol specifications. First published in 2000, it specifies module placement, encoding modes, error correction methods, and mask patterns, among other items.
Denso Wave's declaration not to exercise patent rights applies to use conforming to this standard. Micro QR code specifications are also included. In Japan, the corresponding national standard is JIS X 0510.