In this paper we study ternary trichotomous rules, that allows for three levels of input, positive, neutral and negative and three levels of output, positive, undetermined and negative. We illustrate the
interest of such rules on collective identity functions that deal with formation of clubs. Usually the question addressed is whether the individual quali es or does not, and the answer is either positive or not. In some situations it may be relevant to distinguish between unquali cation and disquali cation.