MaxiCode

MaxiCode is a public domain, machine-readable symbol system originally created and used by United Parcel Service. Suitable for tracking and managing the shipment of packages, it resembles a barcode, but uses dots arranged in a hexagonal grid instead of bars. MaxiCode has been standardised under ISO/IEC 16023.
A MaxiCode symbol (internally called "Bird's Eye", "Target", "dense code", or "UPS code") appears as a 1 inch square, with a bullseye in the middle, surrounded by a pattern of hexagonal dots. It can store about 93 characters of information, and up to 8 MaxiCode symbols can be chained together to convey more data. The centered symmetrical bullseye is useful in automatic symbol location regardless of orientation, and it allows MaxiCode symbols to be scanned even on a package traveling rapidly.
MaxiCode symbology was released by UPS in 1992.
Structured Carrier Message.
MaxiCode symbols using modes 2 and 3 include a "Structured Carrier Message" containing key information about a package. This information is protected with a strong Reed–Solomon error correction code, allowing it to be read even if a portion of the symbol is damaged. These fields include:
The structured portion of the message is stored in the inner area of the symbol, near the bull's-eye pattern. (In modes that do not include a structured portion, the inner area simply stores the beginning of the message.)
Application-specific information.
Irrespective of mode, a variable amount of application-specific information can be encoded in a MaxiCode symbol. This format of this additional data is not strictly defined, and amongst other information may include:
Modes.
UPS labels use Mode 2 or Mode 3 MaxiCodes.