Invisible wrote:

> The impressive thing is, as far as I can tell, almost all barcode 
> scanners support almost all kinds of barcodes. Even though each coding 
> scheme is utterly unrelated to any of the others. God only knows how 
> this is physically possible...

It's actually very simple.  As long as the scanner is close enough, and 
is at the proper angle, all stripes of a given width will appear the 
same to the scanner.  Each bar coding system uses a series of different 
widths to represent each character.  Some systems use only narrow and 
wide stripes (double width), while others will have stripes that are 
three and four times the size of the narrowest stripe.  Generally each 
character is comprised of a set of stripes that add up to a constant 
width (or else the bar codes would appear to have different widths).

As you can see, once the series of widths is in the scanner, 
interpretation becomes a software issues.  If the data doesn't make 
sense under one coding scheme, the scanner can always run the same set 
of width data through another scheme.

Regards,
John

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