> ## Documentation Index > Fetch the complete documentation index at: https://docs.beliefsystems.xyz/llms.txt > Use this file to discover all available pages before exploring further. # Data Boundaries > What the Data API serves and where the rest of the data lives, how staleness is labeled, what happens to a series that resolves or ceases, and the versioning and deprecation policy for /v1. ## What the API serves, and where the rest lives Three lanes carry Belief Systems data. Each is drawn at a fidelity line, and every line is published. | Lane | Carries | Terms | | ------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Data API** and **MCP** (free, keyed) | Latest levels, undelayed. Trailing 90-day history at `1h` or `1d`. The Belief Volatility catalog, latest values, and history over the same window. Completed reconstitution events. Pointers to the snapshots. | [Terms of Service](https://beliefsystems.xyz/terms), Section 7: evaluation, research, and internal business analytics; attribution required; no redistribution; no production or commercial use | | **[Snapshots](/data-access/downloads)** (free, same account) | Full aggregate history since inception, composition membership and target weights, and the reconstitution chain-link arithmetic, as dated CSV bundles with checksums and a citation record | CC BY-NC 4.0 with an editorial-use grant, stated in each bundle | | **License** (Index Services) | Production rights, redistribution, the full-fidelity feed including the per-market panel and full granularity, evaluation archives, and an SLA | Written license through [Index Services](https://beliefsystems.xyz/license) | The API does not carry constituent compositions, the per-market panel, raw NAV, or granularity finer than one hour. Production rights are a conversation, not a parameter. The archive index pages at [beliefsystems.xyz/data/archive](https://beliefsystems.xyz/data/archive) stay public and permanent. A snapshot cited in a paper resolves to a page describing what that snapshot contained, with its checksums, for as long as the record exists. ## Staleness A constituent market whose price data fails the freshness check at computation time makes the resulting value stale. The value still publishes. It publishes labeled. * `stale` appears on every catalog row, on `latest`, and on each individual point in a history series. * `dataQuality` on `latest` gives the counts behind the flag: `freshMarketsCount`, `staleMarketsCount`, `totalMarketsCount`, `freshDataPct`. The flag travels with the value into every channel – API, MCP, and the snapshot files – under [Index Governance](/trust/benchmark-governance). A consumer decides what to do with a stale value; the administrator's obligation is that the consumer always knows. Belief Volatility works differently. A tick that fails a publication gate is **withheld rather than adjusted**: `publicationState` says whether a value published, and no clamped or repaired number is ever presented as a published one. [Belief Volatility methodology](/volatility/methodology) sets out the gates. ## Series lifecycle A series is `active` while it publishes new values, `resolved` once its constituent events have settled, and `ceased` once the administrator has discontinued publication. Cessation outranks resolution: a series that has both settled and ceased reports `ceased`, and `resolvedAt` and `ceasedAt` carry the dates. **Resolved and ceased series keep serving.** History remains queryable and the series remains in the catalog. Cessation ends publication of new values; it never withdraws published ones. Discontinuation notices are dated in the [Governance Log](/trust/governance-log) under the cessation procedure in the [index governance policy](/trust/benchmark-governance). `publicStatus` is the field to key off, on the catalog and on `latest` alike. It is the consumer-facing lifecycle state and it is the one that stays stable. ## Versioning and deprecation `/v1` is **additive-only**. New fields, new endpoints, and new values in existing enumerations may appear at any time, and a client must tolerate them: ignore fields you do not recognize rather than validating against a closed schema. Nothing already published under `/v1` will be removed, renamed, or have its meaning changed. A change that cannot be made additively is published as `/v2`. When that happens: * Both versions serve concurrently for a stated migration window, announced before `/v2` opens. * Responses from the retiring version carry `Deprecation` and `Sunset` headers, so a program learns of the retirement from the traffic it is already making. * The change, the window, and the retirement date are recorded in the [Governance Log](/trust/governance-log). Methodology changes are governed separately and more strictly: a change to how an index level or a Belief Volatility value is computed is published at least five calendar days before it takes effect, with a dated governance entry, and applies prospectively only. Published history is never rewritten. [Index Governance](/trust/benchmark-governance) sets out the full procedure. Distribution changes – a new channel, a new access requirement, a retired endpoint – are recorded in the same log, on the day they take effect.