  Let F be a local henselian nonarchimedean field of residual field k, and let
G be the group of F-points of a connected reductive group defined over F. It is
well-known that the quotient of any parahoric subgroup of G by its first
congruence subgroup is isomorphic to the group of k-points of a reductive group
defined over k, and conversely; in this paper, we generalize this result by
studying a class of linear algebraic groups named groups of parahoric type; we
prove that, under certain conditions, any such group is k-isomorphic to the
quotient of a parahoric subgroup of some reductive group over F by its h-th
congruence subgroup for a suitable h.
