How a date becomes an answer.
The calendar engine turns exchange notices into per-date records. This page describes the source tiers, what “verified” means, the night-session definitions and the limits of what the site asserts.
Source tiers
| Tier | Meaning |
|---|---|
| Official original | The exchange notice itself: HTML page or PDF retrieved from the exchange domain, saved with its SHA-256. |
| Official index | The exchange’s own listing where the notice body could not be fetched directly (WAF or access limits); dates read from the exchange-domain search index. |
| Complete reproduction, cross-checked | Two independent full reproductions of the same notice agree with each other and with every holiday-specific night notice. Used for DCE and CZCE; labelled on every page that depends on it. |
Every source record exposes source_type, check_method, source_checked_at, verified_at and verified_by. A discovery link alone is never evidence for a date.
What “verified” means
- An annual notice (and each holiday-specific night notice) is loaded into the engine as source-checked, with its URL and check date.
- The maintainer compares every closure interval, reopening date, adjusted weekend and pre-holiday evening against the notice and signs off: verified_at and verified_by are written to the record.
- Search indexing opens only when every source behind every loaded calendar is signed; pages for unsigned or unknown dates stay noindex.
- A later exchange notice can amend a date. Amendments are applied field by field, keep their source, and appear on the changelog with the affected dates; an audit re-check never overwrites an earlier assertion.
Night sessions: two dates, two questions
night_session describes the evening that starts on the selected civil date (Beijing time) and applies to eligible products only. incoming_night_session describes the overnight component that belongs to the selected trading date. The evening before a holiday has no night session; the evening of the first day back belongs to the next trading date. GFEX currently lists day sessions only; stock exchanges have no night session.
What is not asserted
- Unknown is null, never closed. A failed fetch or a missing notice does not change a date.
- No live session status, settlement calendar, HKEX derivatives, Stock Connect or point-in-time history. Years without a loaded notice are shown as shells with no dates.
- Overseas venues (SGX, CME, ICE) show representative product hours, not exchange-wide status.
Updates, corrections and citation
Annual notices arrive in December; holiday-specific night notices arrive one to two weeks before each holiday. Loaded notices are listed on the changelog and every page shows its source-check and sign-off dates. Corrections: data@marketsopen.today. Cite a page as “Markets Open, page title, URL, data_version, verified_at” — the same fields the API returns; each indexable page carries a ready-made citation line and a Markdown version (append .md to its path).