Apparently this organization is created in 1952 under a different name, now known as the World Customs Organization (probably changed to be more like WTO), so whatever treaty Customs and Border Protection is talking about must have been a rule-set reset to this organization, not the founding document as I had assumed. This reset is probably analogous to how the General Agreement on Trade and Tariffs mutated into the WTO.

If I weren't running around so much, I think I would have thought of that myself, because when you think of it, you just knew it was one of those international organizations generated after WWII.

So the question for me now in future interactions with CBP is, how is the WCO revamped (apparently, the name change was recent) by this rule-set reset?