Indian Penal Code, 1860
30. "Valuable security"
The words "valuable security" denote a document which is, or purports to be, a document whereby any legal right is created, extended, transferred, restricted, extinguished or released, or where by any person acknowledges that he lies under legal liability, or has not a certain legal right.
A writes his name on the back of a bill of exchange. As the effect of this endorsement is transfer the right to the bill to any person who may become the lawful holder of it, the endorsement is a "valuable security".