Zorkmid (zm) was the unit of currency of the Great Underground Empire.
The authentic zorkmid bore the likeness of Belwit the Flat, the year, and the coin's value on the front, while on the back it had a picture of Egreth Castle, with the motto "In Frobs We Trust" stamped in two different languages.
Zorkmids of different denominations were issued, including the 500 and 10,000 zm coins, and the 100 zm bill. The largest issue was a 100,000 zm bill. Only one of these was ever printed, at the request of J. Pierpont Flathead.