  We extend the $l^2(L^p)$ decoupling theorem of Bourgain-Demeter to the full
class of developable surfaces in $\mathbb{R}^3$. This completes the $l^2$
decoupling theory of the zero Gaussian curvature surfaces that lack planar (or
umbilic) points. Of central interest to our study is the tangent surface
associated to the moment curve.
