carat (keration)
(lat. siliqua) A measure of weight in the Mediterranean world based on the carob seed (Ceratonia siliqua) and weighing 1/1728 of the Roman pound, or 0.189 g. Since the solidus weighed 24 carats, the secondary meaning of carat is 1/24 of pure gold, commonly used today as a measure of the fineness of gold. (Grierson, 1999)

nomisma
A term meaning “coin,” more especially the gold solidus. In the late tenth century it was split into two separate denominations, a heavier histamenon and a lighter tetarteron. From 1092 onward, the heavier coin was generally termed a hyperpyron, while the lighter coin ceased to be struck. (Grierson, 1999)

praefectus urbi (prefect of the city)
(later referred to as the eparch of the city) Αdministrator and virtual governor of Constantinople in the Early/Middle Byzantine Era. He was responsible for the surveillance and the harmonius life of the Capital. One of his responsibilities was to control the commercial and manufacturing activities of Constantinople. After 1204, however, the office began to diminish, while from the 14th century, his responsibilities were assumed by two officers, the so-called kephalatikeuontai of the capital.