We investigate the possibility of developing a decidable logic which allows expressing a large variety of real world specifications. The idea is to define a decidable subset of many-sorted (typed) first- order logic. The motivation is that types simplify the complexity of mixed quantifiers when they quantify over different types. We noticed that many real world verification problems can be formalized by quantifying over different types in such a way that the relations between types remain simple. Our main result is a decidable fragment of many-sorted first-order logic that captures many real world specifications.