duals or organizations that obtain products from a service provider are included here. It represents all types of interactions with the customer and management of customer relationship. The contract operations related to the Fundamentals of EMS, NMS and OSS/BSS customer bills for products, collection of payment, overdue accounts, billing inquiries, and adjustments made as a result of inquiries are all accounted in the customer domain. The customer domain maps to the customer layer in the eTOM model. 5. Service domain: This domain deals with the definition, development, and operational aspects of services. Various eTOM processes that deal with the definition, development, and management of services offered by an enterprise are supported by the SID business entities in service domain. The domain also includes agreement on the service levels to be offered, deployment, and configuration of services. Information definition for other service related activities like management of service problems, service usage, quality of ser- vice, and service planning are covered in service domain. 6. Resource domain: This domain has ABEs managing the definition, develop- ment, and operational aspects resources. The components of the infrastruc- ture and the products and services that use the infrastructure are covered in resource domain. Association of the resources to the products and services provides results in a detailed set of resource entities. The information models to perform planning, configuration, and monitoring are provided by SID in the resource domain. Supplier/partner domain: The data and contract operations associated with a supplier/partner are included here. It includes planning of strate- gies, handling of all types of contact, management of the relationship, and the administration of supplier/partner data. Data and contract operations related to the supplier/partner bills, disputes, and inquiries are also handled in this domain. Another important grouping used in SID is common business entities. These are busines