What are categories?
Categories are attributes of data elements that provide hints to users and user agents as to the intended uses of the data. Categories are vital to making P3P user agents easier to implement and use; they allow users to express more generalized preferences and rules over the exchange of their data. Categories are often included when defining a new element or when referring to data that the user is prompted to type in (as opposed to data stored in the user data repository). Categories themselves are not data-elements, but are a more generalized description of a set of single data-elements, which belong to this category. A single data-element like user.name.personname can belong to multiple categories at the same time. See the Chapter in the Specification for more information.
