Ledger Layer

This layer specifies:

• What the state of the ledger looks like; and

• How the ledger must be updated for each new block.

The ledger layer consists exclusively of pure functions that specify the transitions between successive ledger states, as derived from the formal ledger rules, using the Extended UTXO (EUTXO) accounting model. The state transitions are driven by the set of transactions contained within the Cardano blocks, and by major events such as epoch boundary transitions and hard fork combinator events.

The consensus layer does not need to know the exact nature of the ledger state, nor the contents of the blocks, apart from some header fields required to run the consensus protocol.