Given a contingency table of non-negative reals in which the internal entries do not sum to the corresponding marginals, there is often the need to adjust internal entries to achieve additivity. In many applications, the objective is to have zero entries in the original table remain zero in the revised table and positive entries remain positive. Not all two-way contingency tables can be adjusted to achieve additivity subject to these constraints, and in Fagan and Greenberg (1987), the authors presented a procedure that will determine whether a given table can be so adjusted, and such adjustable tables were called feasible. In Section 4 of this report we present comparable procedures for three-dimensional tables.