Prefix authentication schemes (Meyer, 2023bb) — usually called append-only logs, or transparency logs — are cryptographic schemes to efficiently authenticate total ordering between events. For any two events from a single event stream, you can provide a short digest to certify that one happened before the other (as opposed to them happening concurrently). Reed is a lightweigh specification for implementing the SLLS3​ scheme (Meyer, 2023aa), a scheme that produces shorter proofs than the traditional certificate transparency logs (Laurie et al., 2021).