A single bill is a bill without any condition, and does not depend upon any future event to give it validity. It is a written engagement, generally under seal, for the payment of money, without a penalty.
A single bill may pass by simple endorsement, from one to another, to an indefinite extent, and the last holder, in order to collect it, if bona fide entitled thereto, may fill up the blank endorsement at bar, and recover on the same. [Lucas v. Byrne, 35 Md. 485 (Md. 1872)].