The organizational breakdown structure (OBS) is a hierarchical way to represent the managers responsible for the projects in your enterprise. You can associate the responsible managers with their areas of the enterprise project structure (EPS) with either an EPS node or a project. When you associate a responsible manager with an EPS node, any projects you add to that branch of the EPS are assigned that manager element by default. An OBS supports large projects that involve several project managers with different areas of responsibility.
To access a project, a user must have access permissions for an OBS element within the project. You can then assign users to OBS elements. When you assign users to OBS elements, users get access privileges to projects and EPS nodes where they have OBS access. These access privileges are not passed down to child OBS elements. If some users need access to multiple OBS elements, you must assign those users to all of the OBS elements they need to access. The type of access granted to a user is determined by the project security profile assigned to the user.