A more thorough explanation:

Definition: Dialogus de Scaccario is a historical treatise written during the reign of Henry II about the Court of Exchequer. It is set up in imaginary dialogue form between a master and a disciple. The book explains the machinery of government in minute details.

Example: The Dialogus de Scaccario was probably written by Richard Fitz Nigel, the bishop of London under Richard I, and the former Treasurer of the Exchequer. It is an anonymous book, but there can be little doubt that we are right in ascribing it to Richard Fitz Neal.

Explanation: The example illustrates that the authorship of the Dialogus de Scaccario is attributed to Richard Fitz Nigel, who was a high officer of state and a trusted counsellor of a powerful king. The book was written to explain the machinery of government to all whom it may concern, including the numerous clerks who were learning their business in the exchequer. The book stands out as a unique book in the history of medieval England, perhaps in the history of medieval Europe.