As mentioned earlier, it is necessary to assign or associate Categories and Groups as the Categories are being defined because a Group must be assigned to a Category for the Category Permissions window to be active. Normally, there is one Group per Category, but there is no maximum requirement, so many Categories could be assigned to a Group.
This association is important because, after a resource is assigned to a Group, the resource gets the use permissions assigned to the Group and the data permissions and restrictors assigned to the Category assigned to the Group. This association defines all that a user can do or see while operating in the system.
The Case for Multiple Categories
This section explores a complex data scenario. You want project managers to see all projects in the Project Center but only edit their own projects. Two Categories need to be defined so that the ability to save a project to the database is based on the data criteria of role and permission.
The Project Manager Group would have two associated Categories. One Category would not restrict the projects, so the All Current and Future Projects radio button would be selected. But the Category permissions would allow Open Projects, and the Save Projects permission would be blank. Open Projects and Save Projects are features that control the behavior between Project Professional and Project Server. Open allows the project manager to open all the projects in the database into Project Professional but not save them to the database.
The second Category would select the Only the Projects Indicated Below radio button and then select the security rule Allow Users in This Category to View All Projects They Manage. The permissions Open Projects and Save Projects would be allowed. This data structure would allow the project manager to open and save only those projects for which he was the creator (owner).
The total permissions for a project manager are now set so that the project manager can see all projects (defined by Category 1) but can only edit (open and save) the projects that he created (defined by Category 2). The system understands the association of the user to the Group and the association of the different Categories to the Group to control the users' conditional use of data.