Formal extension and quotients of the invariant holonomic system

Let image be a semisimple Lie algebra and image a Cartan subalgebra of image. Fix image. Let image 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 image. In the sequel we calculate the characteristic variety of some simple quotients of image and its Fourier transform image.