> For the complete documentation index, see [llms.txt](https://raceecosystem.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://raceecosystem.gitbook.io/docs/how-race-tm-chain-works/fault-proof-program.md).

# Fault Proof Program

The Fault Proof Program defines the verification of claims of the state-transition outputs of the L2 rollup as a pure function of L1 data.

The <mark style="color:orange;">`op-program`</mark> is the reference implementation of the program, based on <mark style="color:orange;">`op-node`</mark> and <mark style="color:orange;">`op-geth`</mark> implementations.

**The program consists of:**

* **Prologue:** load the inputs, given minimal bootstrapping, with possible test overrides.
* **Main content:** process the L2 state transition, i.e. derive the state changes from the L1 inputs.
* **Epilogue:** inspect the state changes to verify the claim.