@gorol they also exist in the UK (albeit in a slightly different proprietary format) and are added by Royal Mail sorting equipment in UV sensitive ink, so can be easily overlooked (they are usually a fluorescent orange colour, and you will see them on envelops that have already been through the postal system delivered to your address)
@gorol I think the same company sells the kit to postal services the World over; but what the data contains varies between each country.
The black readable 4 state barcodes do also exist in the UK (and this format or the contents isn't a secret and is widely shown online) but are more often used for bulk mail (especially marketing related mail) from larger companies...
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