case MODIFIED_JULIAN: epoch = "1858-11-17 00:00:00"; days = 2400000.5; break;
case JULIAN: epoch = "4713-01-01 12:00:00"; days = 0; break;
default: throw new AssertionError(e);
}
final String name = e.name();
final TemporalDatum datum = e.datum();
final TemporalCRS crs = e.crs();
final Date origin = datum.getOrigin();
Validators.validate(crs);
assertSame (name, datum, e.datum()); // Datum before CRS creation.
assertSame (name, crs.getDatum(), e.datum()); // Datum after CRS creation.
assertEquals(name, epoch, format(origin));
assertEquals(name, days, origin.getTime() / DAY_LENGTH - julianEpoch, 0);