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This document contains definitions for terms used throughout the Kona book.

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Fault Proof VM

A Fault Proof VM is a virtual machine, commonly supporting a subset of the Linux kernel’s syscalls and a modified subset of an existing reduced instruction set architecture, that is designed to execute verifiable programs. Full specification for the cannon & cannon-rs FPVMs, as an example, is available in the Optimism Monorepo.

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Fault Proof Program

A Fault Proof Program is a program, commonly written in a general-purpose language such as Golang, C, or Rust, that may be compiled down to a compatible Fault Proof VM target and provably executed on that target VM. Examples of Fault Proof Programs include the OP Program, which runs on top of cannon, cannon-rs, and asterisc to verify a claim about the state of an OP Stack layer two.

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Preimage ABI

The Preimage ABI is a specification for a synchronous communication protocol between a client and a host that is used to request and read data from the host’s datastore. Full specifications for the Preimage ABI are available in the Optimism Monorepo.