validate_identifiers

Do these aviation identifiers describe the same thing on this date?

Give any combination of a registration (tail number), a Mode-S 24-bit
address, an ICAO type designator, an operator name, an airline designator
(IATA or ICAO), a callsign and a flight designator, plus as_of. Each
pair that can be checked is checked, and every check comes back with a
verdict -- consistent, contradicted or unverifiable -- the detail,
and the rule that decided it. contradictions lists the failures on
their own so an agent can act on them without reading everything.

The top-level verdict is consistent ONLY when every check verified.
When some checks passed but others could not be checked it is
consistent_where_checkable -- a different answer, because an absent
record silences exactly the checks that would catch a false claim about
that airframe. unverifiable_count says how many checks were silent;
treat anything above zero as partial coverage, not a pass.

Use it before acting on identifiers assembled from more than one message:
a movement message's registration against a surveillance track's address,
a schedule's flight number against the operating airline, a type in a
load message against the airframe's record. One contradiction is a
contradiction; the top-level verdict never averages it away against
the checks that passed.

What the rules are: the registration record on the date (address, type,
operator); a *previous* holder of a re-issued mark is named as such rather
than reported as a mismatch; the FAA allocation arithmetic for N-numbers
(an address decodes to exactly one N-number, so a wrong pairing is provable
without any second source); a military or government airframe is said,
not judged; the airline's callsign against its record and the FAA
contractions order; the carrier inside the flight designator against the
airline given; and whether the type designator exists at all.

unverifiable means this dataset cannot say -- there is no record, or the
record lacks the field -- and is a different answer from consistent. Do
NOT read it as a pass. It does not check hex-to-country for non-US
addresses, performance plausibility (range, block time) or anything live,
and it does not resolve identifiers you did not give it: call the
resolve_* tools for that. Pass as_of for any historical question; marks
and designators are reused and an undated check is silently wrong for
past data.