Required inputs
UTC instant
Leap-second table version
Earth-orientation data version
Ephemeris time-scale requirement
Ordered execution
Work the protocol
- 1
Start from the resolved UTC provenance unit.
- 2
Apply the pinned leap-second relation to TAI.
- 3
Derive TT under the declared convention.
- 4
Use TDB only where the ephemeris requires it.
- 5
Use UT1 only with named Earth-orientation data.
Outputs
- Time-scale chain
- Versioned offsets
- Unavailable-conversion warnings
Done only when
- Every scale has a purpose.
- Every offset is reproducible.
- Unavailable data yields refusal or bounded uncertainty.
Fail closed
Refusal conditions
- UTC and UT1 are treated as synonyms.
- Leap-second or Earth-orientation versions are missing.
- A scale is converted because its label looks similar.