Terminology

Here we introduce terminology specific to this design, especially when it may deviate from other consensus systems or common terminology used in the consensus protocol field.

Crosslink Finality

Crosslink provides a kind of finality which we call crosslink finality. Crosslink finality has these properties:

• It is accountable because the chain contains explicit voting records which indicate each participating finalizer's on-chain behavior.
• It is irreversible within the protocol scope. The only way to "undo" a final block is to modify the software to do so, which requires intervention by the user. Note that because a finality safety violation is always theoretically possible, this implies the only recovery from such a violation is out-of-band to the protocol and requires human intervention.
• It is objectively verifiable because it is possible to determine finality from a local block history without any out-of-band information.
• It is globally consistent meaning that all nodes which have received a sufficient number of valid blocks agree on the finality status, and also can rely on all other nodes in this set arriving at the same conclusion.
• It provides asymmetric cost-of-attack defense (TODO: Describe this better.)