Machine Testimony This document specifies the Testimony Record, an append-only interchange format for the account an automated system gives of its own operation: what it believed, what evidence each belief rested on, which of its beliefs contradicted one another, what actions it attempted, and who authorised the consequential ones. The format is defined so that a party who was not present, and who has no access to the emitting system, can read a record and check specific properties of it. Four conformance levels are defined, each stating a property that can be verified mechanically rather than asserted. This is not a logging format. Logs record what a program did. A Testimony Record states what a system claimed to know, what disagreed with it, and what it was permitted to do about it.