The problem of uncertainty management in systems based on rules can be dealt with using several methodologies. A particularly significant and well-founded one is based on Dempster-Shafer's Theory of Evidence. This methodology is based on the hypothesis that the values of an attribute for a certain object are mutually exclusive. This hypothesis is often too restrictive and the present work proposes a procedure of knowledge acquisition which allows for the application of the D-S theory even in cases where the objects are described, for example, in a linguistically \u2018conventional\u2019 manner, where such a constraint would not be satisfied