visible on network-level 1 will, after the refinement, exist in nodes n2.2.2 and n2.2.3, i.e. in nodes that are defined first on network level 2. When horizontal partitioning is applied, the relations between nodes on adjacent network levels are obviously not hosts relations, but relations that tell how hosts relations that are defined on a higher network level are terminated on the nearest lower. We call such relations term(-inates). A term rela- tion has a hosts relation as its attribute, such as term(h1) in Fig. 4.15. In conclusion: to make a logical-network structure reveal that horizontal parti- tioning has been applied between network levels, term relations must be included in the model. If vertical partitioning (i.e., separating layer elements into parts) had been applied in our case study, no term relations would appear in the logical-net- 4.3 Horizontal Partitioning work structure model. Instead we would insert allo relations between network level 2 nodes and the corresponding layer structure model, as we saw in Fig. 4.2. We will end this discussion by showing all relations of the network system we have used for exemplification (see Fig. 4.16). hosts n1.4.1 € n1.4.2 n1.3.2 n1.3.1 Common hosts n1.3.3 agent hosts layer n1.2.1 nwl.2 nw2.2 n1.2.3 n1.2.6 n2.2.2 n1.2.2 n1.2.4 n2.2.1 n2.2.3 n1.2.5 hosts n2.1.3 n2.1.2 n2.1.1 n2.1.4 n2.1.5 Fig. 4.16 Layer and network structures, and their relations The complete logical-network structure is built by different types of routes, by sub relations and by the three inter-structure relations hosts, term and allo, where: sub defines adjacent network levels within a logical-network structure. hosts defines the relations between hosting and hosted logical networks within the same network level. term defines the relations between nodes on different network levels allo defines the relations between nodes and layers of a corresponding layer structure. This model consists of considerable more network and node definitions than if we had not introduced horizontal partitioning and