What is the origin of the term 'Mark' / 'Mk' ?

I'm curious as to what is the origin of the term Mark (abbreviation Mk) to denote the different versions of some device or group of component elements. So widely used, from cars to planes to musical instruments to bands line-ups... I have even seen it used to denote different stages of governments with a same Prime Minister or President but different ministers.

Well  a  mark is  a  sign.  Like make your mark. show your sign. So this prototype is signed or known as version 1..or Mark 1.

http://www.thefreedictionary.com/Mark

9. Mark - a person who is gullible and easy to take advantage of

It's related to benchmark - which is a measure or reference point. The dictionary (and thus wikipedia) claims benchmark refers to the reference mark made on a surveyors bench ... which I suspect is wrong as surveyor's don't have benches, it is more likely they borrowed the term from carpenters who used to make a chalk-mark on their work-benches to cut several pieces of wood to the same length. From there benchmark came to mean "standard" both literally and figuratively.