In this paper we study the dynamic disturbance decoupling problem for
nonlinear discrete-time systems that are considered in a neighbourhood
of a given reference trajectory. Furthermore the connection between t
he solvability of this problem and the solvability of the correspondin
g problem for the time-varying linear discrete-time system obtained by
linearizing the original system along the given reference trajectory
is investigated. For this purpose, a geometric disturbance decoupling
theory for time-varying linear discrete-time systems is developed.