ns for all routes that terminate in a logical node are stored in a route-endpoint table (T-RE) in the logical node. These tables are normally set and updated from a central management system although decentralized updating (by special protocols between the logical nodes themselves) exists as well. The model in Fig. 3.8 exemplifies that the routes on which a logical node relies can be realized by several hosting networks. These may be of different types, which implies that they define different types of addressing. In general, therefore, the REdef for a route must comprise two parts: a hosting-network identifier (NWi) and a number of address parameters (AddrPar) for that network. Each network system may define its own address parameters. This is because they operate differently. For example, a network that offers switched on-demand services requires a destination network address (destination NA). Some networks require an access-point identifier (APi), others don't. There are also networks that accept names of hosted nodes as address parameter. These networks commonly refer to this address parameter as a global title (GT). We must live with such differences in addressing. However, hosting networks that operate in a similar way (e.g., MTP L3, IP and X.25 datagram), and therefore offer the same type of address parameters to hosted networks, use (with no excep- tion) different parameter names. This is a very unfortunate state of affairs for eve- rybody who tries to understand network system other than those already known. Figure 3.9 gives an overview of address parameters and names used in a number of well-known network systems. The symbols shown in the right-most column may be used as annotations for functional elements and logical nodes in models to denote the type of relaying (or "transfer mode"). Since there are only three types of address parameters that are needed for routes (GT, NA, APi), the table exemplifies how one can complicate things by not using the same name for the same thing. For example, instead of c