What is Apposer?

Legal Definition
An officer in the exchequer, clothed with the duty of examining the sheriffs in respect of their accounts. Usually called the "foreign apposer." Termes de la Ley.
-- Black's Law Dictionary
Legal Definition
Eng. law. An officer of the Court of Exchequer, called the foreign apposer.
-- Bouviers Law Dictionary
Legal Definition
An officer who supervised the accounts rendered to the exchequer by the sheriffs.
-- Ballentine's Law Dictionary