Module scale 

Frozen scale set.

Every scale is a zero-sized marker type that identifies a scientifically distinct time axis. The Scale trait is sealed — downstream crates cannot add new scales.

• Coordinate scales (TAI, TT, TDB, TCG, TCB, UT1, UTC) implement CoordinateScale and support raw-axis constructors, accessors, and instant arithmetic on Time<S>.
• The civil scale UTC still does not implement ContinuousScale: it shares the internal instant axis used by TAI, but civil labels and leap-second interpretation remain table-driven.

Structs

BDT

BeiDou Navigation Satellite System Time. BDT = TAI − 33 s (nominal, exact integer offset). Equivalently BDT = GPST − 14 s.

ET

NAIF/SPICE Ephemeris Time — compatibility marker.

GPST

GPS System Time. GPST = TAI − 19 s (nominal, exact integer offset).

GST

Galileo System Time. Nominally GST = TAI − 19 s (identical tick rate and integer offset to GPST today; broadcast inter-system offset GGTO is not modeled here).

QZSST

Quasi-Zenith Satellite System Time. Nominally aligned with GPST (QZSST = TAI − 19 s). The QZSS ICD defines QZSST as steered to GPST; observed inter-system offsets are not part of the scale.

TAI

International Atomic Time. Continuous SI-second clock.

TCB

Barycentric Coordinate Time (IAU 2006 B3). Linear relation to TDB.

TCG

Geocentric Coordinate Time (IAU 2000 B1.9). Linear rate difference to TT.

TDB

Barycentric Dynamical Time.

TT

Terrestrial Time. The dynamical reference scale in this crate.

UT1

Universal Time 1 — Earth-rotation time axis.

UTC

Coordinated Universal Time.

Traits

ContinuousScale

Witness that a scale is both coordinate-bearing and physically continuous.

CoordinateScale

Witness that a scale is continuous and supports direct arithmetic. UTC deliberately does not implement this: it has raw-axis accessors through CoordinateScale, but its civil interpretation remains leap-second-aware and table-driven.

Scale

Marker trait for a scientifically distinct time scale.