What unit of measurement does the Imperial Unit setting use?

I’m using Blender 2.76, and I set the measurement unit to “Imperial,” and I was just curious as to what specific measurement it uses. Does it use inches, feet, yards?
Thanks in advance,

There should be a unit preset drop down box in the same tab. You can choose what measurement you want to use or create a custom one.

Does it use inches, feet, yards?

Yes. Chains, too!

The odd thing about Imperial measurements in Blender is, 2 feet in Imperial is 2 meters in metric. It doesn’t actually convert, it just substitutes feet for meters. Unless there’s another setting I’m missing?