Abstract: The code is scanned along at least four non-coincident parallel lines in a bar code reading device. The actual processing is started when a margin of sufficient width is detected. The width of the bar is counted and the width found is used to address a table memory. This results in a width indication for a valid bar and a reset signal for an invalid bar. There is provided an bar counter which counts the bars and which addresses a bar memory in order to store the bar identification therein. When the reset signal is received, the series of bar identification received thus far for the relevant line is invalidated, unless all bars of a complete code have already been received. During validation a check is performed as regards correct contents and possibly correspondence between two potentially correct bar codes found.