Patent ID: 8360333

Claim:
An optically readable two dimensional symbol, comprising: a finder structure comprised of a solid border defining the perimeter of an area, said border being shared with neighboring areas, each of said areas having first and second major axes which are substantially perpendicular to one another; each said area having within its perimeter an internal bi-directional data representation structure comprised of one or more locations in each of the horizontal and vertical directions, named respectively rows and columns, with each of row being filled with one or more horizontal lines or spaces, and each column being filled with one or more vertical lines or spaces, in order to represent the zero or one bits of a binary signal; a data block representation structure formed by the grouping into bytes of said bits, said block being comprised of one or more block data bytes and two or more block error check bytes that encode error correction data for the block; an overall symbol data representation structure comprised of one or more data groups, each said group comprised of three or more data bytes from said data blocks, with each group containing one or more data bytes and two or more group error check bytes that encode error correction data for each said individual group, the ratio of group bytes to error correction check bytes being selectable from one or more discrete group ECC levels; and a superblock structure used to define a prefix value for each said data block, said superblock being formed by the grouping of four neighboring data blocks, wherein said prefix value is a function of each individual data block geographic location within the symbol and the symbol ECC level.