In a train dispatching system for controlling the movement of plural trains over plural track resources, the plural track resources being defined by domain data, a method of modifying the domain data comprising: (a) developing a first change set of intended modifications to the domain data, (b) developing a second change set of intended modifications to the domain data which reverses the modifications made by the first change set, (c) implementing the first change set to a domain data baseline, (d) evaluating the implementation of the first change set against a predetermined criteria; and (e) implementing the second change set if the evaluation of the first change set does not satisfy the predetermined criteria to return the domain data to the domain data baseline.