Formal extension and quotients of the invariant holonomic system

Let g be a semisimple Lie algebra and h a Cartan subalgebra of g. Fix λ∈h∗. Let Nλ be the invariant holonomic system (see [R. Hotta, M. Kashiwara, The invariant holonomic system on a semisimple Lie algebra, Invent. Math. 75 (1984) 327-358]). First we investigate its formal extension Nˆλ. In the sequel we calculate the characteristic variety of some simple quotients of N0 and its Fourier transform N0F.