A process model is a hierarchy which structures business domains, business processes, and activities. A business domain is a cohesive portion of the business used as the scope for a reengineering or analysis activity. A business process is a flow of work through a business domain to produce a deliverable of value (it is functional in nature). An activity is a subdivision of a business process which is assigned to a particular business entity for performance. This hierarchy places a business domain or business process at the highest level in the model, which is referred to as the model's root. More specific business domains or processes are positioned below the root. Business domains may contain child business processes which themselves consist of component activities. The lower in the hierarchy the child appears, the more detailed (smaller) its scope.
During a business process reengineering effort, the scope of the project is typically expressed as a single business domain. Such a domain covers a significant portion, if not all, of the business. A series of activities and interim deliverables flow through this domain to produce the major business deliverables. Each of these flows is referred to as a business process. The business processes are organized below the business domain in the hierarchy. The component activities that accomplish each business process appear below the process to further detail the hierarchy.
The scope of a business object analysis effort is also expressed as a single business domain. The scope of this more detailed analysis effort may only be a single business process or portion of a business process. The business domain addressed by the analysis effort is typically not divided into component business domains. However, the results of multiple analysis efforts can be combined into a larger business domain and shown with a hierarchy. Although the creation of the model is straightforward, the effort to resolve inconsistent semantics between the component business domains is a complex activity.