The Goal-Service Model can be thought of as going through two elaborations.  The first elaboration captures the initial structure of goals, sub-goals, KPIs and metrics for the project, and maps goals and sub-goals to candidate services where possible.  At the end of this elaboration there may be goals or sub-goals that do not yet map to a service. 

The second elaboration takes place when making service exposure decisions, during which candidate services are evaluated for business alignment.  Any service that is going to be chosen for exposure must map to at least one goal or sub-goal in the Goal-Service Model.  This can result in an update to the Goal-Service Model to document the service mapping, and potentially to add a new goal or sub-goal (subject to careful evaluation for fit with business objectives).

Goal-Service Modeling, similar to other SOMA activities, is typically carried out using an approach that incrementally builds a Goal-Service Model through several iterations.  One area of the Goal-Service Model may be found to be complete to the point described for the first elaboration, while another portion may already complete to the point described for the second elaboration.  Eventually additional iterations of Goal-Service Modeling and Service Exposure Decisions will result in a Goal-Service Model that has been completed to the second level of elaboration for all areas of the model that are necessary to complete the current project.

The information needed to create an instance of the Goal-Service Model work product can be gathered through interviews and facilitated work sessions.  To provide structure for the interviews or work sessions, an instance of the Goal-Service Model template can be filled out during the sessions, providing all participants with a visible and evolving framework of goals and sub-goals.