  Unlike Legendrian submanifolds, the deformation problem of coisotropic
submanifolds can be obstructed. Starting from this observation, we single out
in the contact setting the special class of integral coisotropic submanifolds
as the direct generalization of Legendrian submanifolds for what concerns
deformation and moduli theory. Indeed, being integral coisotropic is proved to
be a rigid condition, and moreover the integral coisotropic deformation problem
is unobstructed with discrete moduli space.
