Indenture

A service contract. In days of yore, before copy machines changed our lives, contracts were written and signed in duplicate on the same parchment, which was then torn, or cut in a zig-zag line, down the middle, each half going to one of the signers. The indentations could later be used to prove that the two parts belonged together –– which explains how contracts came to be called “indentures.” Isn’t this exciting?