As one does when in doubt, you just quote @quuador :
@quuador said: 23 January 2018 at 20:20 Quuador posted on reddit:
The 1999-2000 print run was actually the 8th print run of the Base Set. The 1st print run were the 1st edition Shadowless cards (which can be divided into Thick and Thin 1st edition stamp print runs for the holos); 2nd was the non-1st Shadowless print run; 3rd-7th were the ©1999 unlimited edition; and the 8th was the ©1999-2000 print run in a factory in the UK. They are better known as the 4th print run however, due to the four unique differences: 1. 1st edition Shadowless; 2. non-1st Shadowless; 3. ©1999 unlimited; 4. ©1999-2000 unlimited. This above is a summary from a quote of cullers on the E4 Forum, which I will also quote here:
@cullers said: 16 May 2017 at 06:49 cullers posted on E4:
Let’s just set this straight and give some people some more inside info on what actually happened. This is more info then any casual collector is going to know and is a good reason to be a part of the forum.
Wizards of the coast starts production on Base set pokemon cards. They use the shadowless template and create a bunch of cards. Some of those cards are given a Thick 1st edition stamp. Some time goes by and they realize they miscaluculated the amount of Holo cards they needed stamped, so some shadowles holo sheet go back and get Thin 1st edition stamps applied. (We know some non holo cards got thin stamps applied to them, but I haven’t seen any factory rep explain why. Speculations have been made, but nothing confirmed).
The 1st edition cards are sold and sent out. Wizards still have a bunch of shadowless sheets which they cut up and sell as the intended ‘unlimited’ version. After this Wizards makes aesthetic and text correction to the templates and starts producing more cards. These new cards have shadows applied to them, and are sold off as unlimited cards. People notice the difference and start calling the old unlimited cards Shadowless.
There’s 6 more print runs done with these changes. The 8th and final print run includes the final corrections made (Vulpix’s HP) as well as the copywrite date changed to 1999-2000. This print was done in a factory in the UK, and most of the packs have regular holo cards (2nd-7th print) put inside them.
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They were printed somewhere in the first four months of 2000 (I’m not sure about the exact date). The cards themselves are the same as their ©1999 counter-parts, except for the change in copyright date (and the Vulpix HP 50 error has been corrected to 50 HP). ©1999-2000 booster packs still contained ©1999 holos sometimes, which makes the ©1999-2000 holos harder to find than the ©1999-2000 non-holos.
I’ve also heard some rumors about ©1999-2000 Base Set being printed very briefly in Australia and Poland, but I haven’t been able to find any confirmation for that. We do know they were printed in the UK for fact, which is why they are also known as the UK Base Set print.
Some slightly off-topic but interesting and semi-relative topics:
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