Case 07 of 26
Historical time zones
Beijing 1990: historical daylight saving applies
China observed daylight saving time on this synthetic summer date.
Boundary question
Does the engine use the historical +09:00 clock offset rather than modern +08:00?
Yes. IANA history supplies UTC+09:00 with a 60-minute DST component, and the corrected solar time becomes 10:45.
Synthetic input
Recorded facts
- Date
- 1990-06-15
- Recorded time
- 12:00
- Location
- Beijing, China
- Time zone
- Asia/Shanghai
- Longitude
- 116.4074°
- Gender input
- Male
Pinned expected facts
Verified output
Year
庚午
Month
壬午
Day
辛亥
Hour
癸巳
- Day Master
- 辛
- True solar time
- 1990-06-15 10:45
- Total correction
- -74.40 minutes
- Historical offset
- UTC+09:00 · DST 60 min
- Luck direction
- 顺排
- Reference Jie
- 小暑 · 1990-07-07 17:00:28
- Luck start
- 1997-11-16 16:29:36
Conventions and limits
What this case does — and does not — prove
It verifies
Deterministic reproduction of this input under the named engine version and conventions. A pinned-field mismatch stops the production build.
It does not claim
Universal agreement across Bazi schools, interpretation of a real person, or certainty where the historical record is incomplete.
tyme4ts 1.5.2 · cantian-tymext 0.0.27 · sect 2 day boundary · BaziCalculator.ai NOAA/IANA true-solar adapter
calculation-benchmarks-v1 · reviewed 2026-09-05