With a limit of 10 million different serial numbers, I wonder how China does it. I can't come up with a decent estimate, and maybe I'm way off. But with the growth of sellers like Shein or Temu, I wouldn't be surprised if they shipped that many parcels in like a single day ? Or at least in a timeframe short enough that they would have over 10 million shipped but yet-to-be-delivered parcels, effectively running out of tracking numbers.
xattt•11h ago
You could hate it by an internal metric, like date received.
Scoundreller•10h ago
What helps is that they don’t ship direct from China by mail much. They often send in bulk to the destination country and then mail locally, and local post systems can have their own domestic format.
Or they have their own private courier do the last mile delivery too so it never touches any postal operator.
bravesoul2•9h ago
Do they? In Australia usually get them direct from HK or China because it is cheaper to do that even than post it within Australia!
wombatpm•9h ago
Service type and serial need to be unique. Countries control what that 2letter field means. There is no rule against multiple codes indicating the same service. So AA through AZ would give you 260,000,000 unique combinations that you shouldn’t reuse for 1 year. Rinse, later and repeat if you need more.
mongol•9h ago
And I wonder what was the constraint to not make it longer when they developed the standard. Making it a few digits more seem it wouldn't cost much.
omcnoe•8h ago
The cost will be in updating every legacy postal system that currently has fixed column lengths/input field length limits.
topsecret•3h ago
Yes, now, but the person you're replying to was asking about at inception.
Sharlin•9h ago
Yeah. Apparently last year they shipped over two million small parcels to Finland (pop. 5.6M) alone, which is completely bollocks.
benced•8h ago
Even the US must easily run into this constraint.
forth_fool•8h ago
Isn't 8 digits closer to 100 million unique numbers than to 10?
notpushkin•6h ago
It’s exactly 100 million unique numbers.
akpa1•3h ago
Author here - yep! It is, that was a typo in the article.
mianm•2h ago
BTW, the correction in the post has the year as 2026 instead of 2025.
akpa1•2h ago
Ha, thanks for the heads up
bloak•8h ago
Does that complex algorithm for the check digit have any advantage over the much simpler algorithm used for EANs or 13-digit ISBNs?
nojs•1h ago
I’m surprised this article didn’t mention the LPC code [1]
Ecco•11h ago
xattt•11h ago
Scoundreller•10h ago
Or they have their own private courier do the last mile delivery too so it never touches any postal operator.
bravesoul2•9h ago
wombatpm•9h ago
mongol•9h ago
omcnoe•8h ago
topsecret•3h ago
Sharlin•9h ago
benced•8h ago