A bi-directional two-dimensional (2D) matrix barcode symbology for use with bar code, cell phones and other optical readers. A finder structure includes indicia for locating data blocks containing bytes of information encoded through bi-directional and orthogonal lines containing individual bits of information. Individual blocks contain error correction information, and are formed into 2×2 superblocks used to build larger codes. Intrinsic prefix information provides a redundant geometric identification for individual blocks within the overall structure, providing a built-in mapping of the overall structure, even when portions are missing or undecodable. The overall symbol has a second set of error correction parameters for further redundancy. The symbology is a versatile symbology in that the number of check data blocks is user selectable to provide the desired level of error correction.