As I recall, the admittedly tepidly-named "Sequence" space was a space whose Positions were an ordered sequence of positions in some other space. Thus, TumblerSpace is properly Sequence<Integer>. I was pretty sure that Tumblers were still around, since everybody loved the name too :) (But they were certainly not as central as they used to be.)
There was another parameterized space, maybe called Box?, which would describe a multidimensional space. For example, an Edition in the space Box<IEEE64,IEEE64,IEEE64> could describe a CAD drawing. Add an integer dimension for part numbers and you can describe parts in a Cad drawing. Or link objects in the space to associated documents.