 1 processes are split into vertical or end-to-end and horizontal or functional groupings, with the dependent Level 2 processes positioned within the vertical and the horizontal group- ing appropriate to the process concerned. As described in the process methodology, eTOM uses hierarchical decomposition to structure the business processes. Through hierarchical decomposition, complex entities can be structured and understood by means of the formalization of their components. Hierarchical decomposition enables detail to be defined in a structured way. Hierarchical decom- position also allows the framework to be adopted at some levels as appropriate but not at others. For the eTOM, each process element has a detailed description that includes the purpose of the process, its basic inputs and outputs, its interfaces, high-level informa- tion requirements and business rules. The eTOM process model also depicts process flow in a way that drives end-to-end process and process flow-through between the customer and the supporting services, resources and suppliers/partners. Based on this process modeling approach, the eTOM process work starts at the Enterprise level, called Level 0, and shows the Level 1 processes (see Figure 9.2). Each Level 1 process is decomposed into its Level 2 component processes. Decomposition is continued until the detail level of the process elements has reached the stage where it is appropriate to define a process flow. 9.6 Conclusion The eTOM is an enterprise process framework for service providers. The processes of the enterprise fall into four major categories with 12 enterprise level process groupings. 9 Telemanagement Forum: eTOM The main strengths of the eTOM framework are that: It is consistent with, and enhances, the well-established TOM. While addressing operations and maintenance, it also covers all significant enter- prise process areas. It is e-business oriented, introducing concepts such as retention and loyalty, a new business relationship context model and supplier/partner relations