 defining the Lli for each layer interface, and then define the platform application address (PA) of the layer elements that connect to the endpoints of a layer interface. The translation between NWi and Lli is then defined in a T-LI table, and the definitions of platform addresses are defined in a T-PA table for the particular platform. Figure 3.14 shows the corresponding tables for the layer structure of Fig. 3.13. All elements of this model are assumed to run on the same platform (which may be a simulator). The platform addresses of these elements are defined for each Lli in the T-PA table as hostingPA and hostedPA respectively. Logically, the depicted scenario goes as follows: 3.3 Route Properties and Symbols hostingPA hostedPA REdef AddrPar Platform application REdef AddrPar nw01AddrPar(n12) nw02AddrPar(n13) nw02AddrPar(n14) nw02AddrPar(n15) nw01AddrPar(n12) stratum stratum Fig. 3.14 An executable layer structure. All layer elements are also platform applications. Lli=layer-interface identifier; PA=platform address Element A (in node n31) wants to send something to n32. Its T-RE table shows that n32 can be used as address parameter and the hosting network is nw1. A gets the platform address (C) to nw1 through its T-LI and the T-PA tables. The address parameter n32 together with message data are sent over the platform, referring C. C (in node n11) reads the address parameter n32 and finds via its T-GT and T-RE tables that the data are to be sent over nw01. C gets the platform address (D) to nw01 through its T-LI and the T-PA table, and sends the data over the platform, referring D. Note that the only table that depends on the actual platform is the T-PA. Thus, the same model can be run on different platforms just by associating it with a rele- vant T-PA. Note also that in real simulation and execution, the T-LI and the T-PA tables are not run-time tables, but data that will be used for compilation of the model. Route Properties and Symbols The properties of routes must be specified in network models. To produ