Universal Product Code Question

[sysreset]

People are coming up with new products all over the world every day. So how is it that no two products ever have the same Universal Product Code (Bar Code) at the same time? Or do they?

 

[Danger]

I don't know how to calculate the number of possible combinations encoded, but I'm pretty sure that it exceeds the possible number of products on the planet.

 

[makethings]

There are also products that go out of date, become obsolete take that into account.

 

[Snazzy]

Well, you've got 10^12 possible numbers. Can you honestly find one billion (or one trillion, depending on where you live) products in this world?

 

[tribdog]

Well, you've got 10^12 possible numbers. Can you honestly find one billion (or one trillion, depending on where you live) products in this world?

You ever been to WalMart?

 

[sysreset]

I was just wondering if large stores just leave it to chance and probability that they won't accidently end up with a winter coat and a tennis racquet with the same code, or if there is some centralized process involved. Particularly if the same computer program is used to generate codes simultaneously in two locations.

 

[jim mcnamara]

There is what amounts to a bar code registry - but foreign manufacturers do not play by the game. The UPC convention is only in US and Canada. So there is duplication.

Plus, all stores have the option of generating their own in-house UPC - as long as the UPC starts with a 2.

Ever see a box with several UPC's or one with another UPC label slapped over another?
Ever bring a box up to a register and find that the register cannot figure out what it is?
The PLU fails because the UPC has not been entered into the local store's system.

In other words, it is not a "unviersal" barcode.