[kbecker] No, the tanker is three dimensional on the two dimension glass ocean, and being a model, it needn’t be filled with oil. One could fill it with Cutty Sark scotch as a Klein hip flask.

Ow! I've just been looking at the Klein Botttle website. My head hurts!

Check out the page I've linked. Look at the diagrams of topological equivalents. Does "sausage" look vaguely familiar? (Stop sniggering at the back, there!)

I think the proposal to use the 2D "sausage" representation to mean 0/0 (or "indefinity") has a distinctly halfbakerish flavour.

The mathematical version is more complex than that, Voice. It exists only in 4D space, and has no intersection between the neck and body where the 3D approximation does.