Is there are classification of the equivalent of a developable surface in $\mathbb{R}^4$?
Analogous to: planes, cylinders, cones, and tangent developables in $\mathbb{R}^3$?
I would appreciate any suggestions for source materials here.  My only source is one page (p.342) in Hilbert and Cohn-Vossen (_Geometry and the Imagination_), in which they say: in $\mathbb{R}^4$

> there are surfaces that are isometric to the Euclidean plane in the small but are not ruled.

A precise definition of _developable surface_ in $\mathbb{R}^d$ would also be much appreciated.
Thanks for pointers!