To facilitate the decoding of a 2D symbol (e.g., PDF417), a plurality of positioning lines are attached to the 2D symbol. Depending on implementation, these substantially parallel positioning lines may be provided on at least one side of the symbol or superimposed on the symbol. A scanning device is...http://www.google.com.au/patents/US6802450?utm_source=gb-gplus-sharePatent US6802450 - Guiding a scanning device to decode 2D symbols
