Many system users may share a topic of interest, and depending on the viewpoint from which a user is looking at the topic of interest, different aspects of the topic become more prominent. Similarly, many system users may work on the same project, but the users have different concerns and may place importance on different aspects of the project, for example, depending on the role a user has in the project, or the user's goals or commitments. Sometimes, however, it may be useful to view the same topic of interest from a different angle, that is, from a different user's viewpoint or perspective.