Deed polls

Just read this:

A deed is a written legal agreement that has been signed and delivered (shown to all concerned parties).  Poll is an old English word used to describe a legal document that had its edges cut (polled) so they were straight.  This was done to visually distinguish between a deed signed by one person (a polled deed - hence the term Deed Poll) and a deed signed by more than one person (an indenture), which had an edge indented or serrated.  Interestingly, indentures were originally written twice (side by side) on one piece of parchment, which was then torn down the middle and each half given to each party.  The impossibility of matching the tear was a guard against forgery.

In England, a "deed poll" is synonymous with changing your name.

This is also where the term "indentured servant" came from.