A more thorough explanation:

Definition: Ab epistolis (ab ee-pis-tə-lis) is a Latin term used in history to refer to an officer who was responsible for maintaining the correspondence (epistolae) for a superior. This officer was essentially a secretary.

During the Roman Empire, the ab epistolis was an important position in the imperial court. The officer was responsible for drafting and sending letters on behalf of the emperor to other officials, governors, and foreign leaders. The ab epistolis was also responsible for receiving and organizing incoming correspondence.

In medieval Europe, the ab epistolis was a common position in the royal court. The officer was responsible for managing the king's correspondence with other monarchs, nobles, and church officials. The ab epistolis was often a trusted advisor to the king and played an important role in shaping royal policy.

These examples illustrate how the ab epistolis was an important figure in the administration of government and the management of official correspondence. The officer was responsible for ensuring that important messages were delivered accurately and in a timely manner, and played a key role in maintaining diplomatic relations between different states and kingdoms.