Abstract: A machine readable code in a form such as a bar code uses self-addressed address/data packets which can be positioned in arbitrary orders and configurations. Additional benefits, such as ability to use extended scan angles for decoding and reduction in required code management data, also result from the self-contained nature of the address/data packet components of packet codes. A sequence of data is separated into units of data which are encoded in data portions of packets each also including an address portion which identifies the position of such data unit relative to the original sequence of data. The individual packets may then be positioned in a wide variety of configurations, rectangular and otherwise, with the individual packets in any order, sequential or otherwise. Even where packets are aligned in an extended row, the usable scan angle range is determined by the width to height aspect ratio of individual packets and not limited by the much higher aspect ratio of the row of packets.

Abstract: The reading and decoding of two-dimensional bar codes in a bar code reader are simplified and field loading of different data character sets is enabled. Decoding of bar/space patterns of a bar code is simplified by deriving T-sequence data representative of the bar/space pattern and then processing a majority of the T-sequences directly into decoded values representative of the bar/space pattern. Dynamic loading of new data character sets fully or partially superseding a factory installed default character set correlation listing is enabled by use of loadable correlation listings keyed to foreign language characters, symbols, words or phrases relevant to particular applications. The loadable correlation listings can be encoded into a two-dimensional bar code and loaded via a reading of the bar code by the bar code reader.