> For the complete documentation index, see [llms.txt](https://docs.force.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.force.xyz/resources/data-sources-and-reliability.md).

# Data Sources and Reliability

The oracle is built on three kinds of input. They are described here by role rather than by vendor, because the methodology depends on the role and not on who supplies it.

| Feed                    | What it carries                                                                                                                                       | Which session uses it  |
| ----------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------- |
| **Cash Feed**           | The on-the-run 10-year Treasury yield, during Treasury market hours                                                                                   | Cash                   |
| **Futures Feed**        | A Treasury futures contract whose deliverable notes carry roughly nine and a half to ten years of remaining maturity, trading nearly around the clock | Extended               |
| **Daily Mortgage Mark** | A daily 30-year fixed mortgage rate index, published each business morning and describing the previous day's lending                                  | Cash, for FORCE-MORT30 |

Each is sourced from institutional market-data providers, and each has a second provider behind it.

## How failure is handled

**Freshness, not heartbeats.** Every feed carries a timestamp and a maximum age. A value older than its bound is not used. A feed that stops publishing therefore drops out on its own, with no separate health check to get stuck.

**Fall back one step at a time.** A stale primary provider moves to the backup provider in the same session. Only when every provider for a session is stale does the oracle move to the next session down. The oracle does not blend feeds; it selects one.

**Withhold rather than publish a bad print.** If no session can produce a valid value, the oracle publishes nothing and the exchange holds the last value it was given. Asserting a price that is known to be stale is worse than asserting nothing.

**The published value is stamped.** Every point carries the session that produced it, so a consumer can always tell a directly observed price from a modelled one.

## What this does not protect against

A provider that publishes a wrong value confidently and on time will be used, because it is fresh. Cross-provider outlier checks reduce this risk but do not eliminate it. The mark price is the layer that limits the damage: it is the median of three independently derived components, so a single bad oracle print does not by itself move the mark. See [Mark Price](/perp-mechanics/mark-price.md).


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