In the paper, the conceptual apparatus (the ontology OntoReg) is presented for designing the Knowledge Based System (KBS ). An original methodology of designing an applied ontology has been developed on the basis of the concept of Roman Ingarden’s individual object as well as the concept of Rudolf Carnap’s constructional systems (Aufbau). According to the procedure of creating an applied ontology, the original ontology of the region (OntoReg) has been developed, with particular emphasis on the characteristics of the region with the distinction of properties at three levels of the constructional system. At the first level, absolutely own properties, acquired properties and externally conditioned properties are distinguished. At the second level, positive states of objects (potentials of the region: geographical potential, social potential, innovative potential, institutional potential) and negative states of objects (risk of implementing the regional development strategy: project implementation risk, environmental risk, institutional risk, public health and safety risk) are defined. At the third level, the indicators of the respective types of potential and risk are considered. The relative characteristics of the comparative assessment between the indicator values for a given potential/risk and a reference value established in scientific research are determined. Determining the relative properties constitutes new knowledge generated due to the ontology constructed.