An RPG of mine (a perpetual project) is similar in concept; I blended the works of Robert A. Heinlein and David Brin with a bit of my own ideas to come up with a six-axis time/space: x, y, z, t, τ, т (ex, why, zed, tee, tau, teh) (those last two are Greek and Russian, respectively)
A space-time manifold, otherwise called a "universe" or "reality" uses four of the six axes, with each axis perpendicular (90 degrees) from the rest.
A space-time fractal manifold, or "multiverse" includes all of the derivatives of the of the original space-time. This is the realm of probability physics; instability occurs when the axes are not the same degree of derivation.
A time/space manifold contains all of the space-time manifolds. A time/space fractal manifold contains every possible space-time and their derivatives.
There's more to it all, of course, but this is enough to get the general idea...