Discount instruments are securities that are issued and traded at a discount to their face value.
Depending on the market, their prices may be quoted conventionally in the market either on a discount basis or on a yield basis.
Discount instruments quoted on a discount basis include bills of exchange and US domestic commercial paper (USCP).
Discount instruments quoted on a yield basis include sterling commercial paper (SCP) when issued at a discount.
(However, SCP may also be issued on an interest bearing basis.)