Merlin provides two objects: a transcript, which models the public interactions between a prover and a verifier, and a transcript RNG, which uses the transcript to provide defense-in-depth against bad entropy attacks.
This chapter describes how these objects are constructed and the operations they can perform:
Transcript Operations describes the transcript object.
Generating Randomness describes the transcript-based RNG.
The next chapter, Using Merlin, describes how to use Merlin to implement a proof protocol.