If you've never heard of this term before, allow me to be the first to introduce it to you.
"Unbroken Floorspace" refers to the amount of floorspace in an enclosure-- there no walls/barriers, it is one large space. This is important when calculating the amount of floor space an enclosure has, just to be clear... "more levels does not equal more floorspace"
For example:
Basically... you can't multiply the base square inches by however many levels there are.
Make sure when you are looking for an enclosure, that it meets the unbroken floorspace minimum!! The Happy Hamstery enclosure available for preorder now has 1200 sq in of unbroken floor space!