Data has a set of permissions that can be different from the object's permission properties. An administrator may have full access to objects, but not have Read permissions on the data.
When defining security permissions for users in the items and portfolios hierarchy, data security should be defined as well. Data security is defined either when selecting a permission set or when defining security in the Security Settings dialog box. For example, when selecting the Read permission set, you get Read permission on the item, its workbook objects, and its data.
There are two ways to define data security settings. Items and Portfolios can define the data security (for the category).
However, you can set categories to define data permissions. When you define security permissions for users in a category, you define if the category or its items define the data security.
By default, items and portfolios define data security.
In categories that define the data security, data security is defined either when selecting a permission set, or in the Security Settings dialog box. For example, if you select the Read permissions set, you get Read permission on both the category and data.