Data integrity verification.

摘要

A method and apparatus for verifying the integrity of data applied to a body from two sources has a strobe head 14a adapted to give an output signal when the presence of a strobe marker 12 is detected to initiate a reading of further data by read heads 14b to 14d. Part of the further data comprises a binary code sub-set 13 printed with the strobe mark 12, and a second set of data, indicative of a code line printed in a second separate printing stage. A comparator compared the reading of the binary code with the reading of the second set of data. If a predetermined relationship between the two readings is not established, an output signal indicative of a mis-match is generated.