Designing Policy Based Management in Microsoft SQL Server 2008
Policy categories can be used to group one or more policies into a single compliance unit. If not specified, all policies belong to the DEFAULT category. To check or enforce policies, you create a subscription to one or more policies.
Subscription occurs at two levels—instance and database. A member of the sysadmin role can subscribe an instance to a policy category. Once subscribed, the owner of each database within the instance can subscribe their database to a policy category.
Each policy category has a Mandate property that applies to databases. When a policy category is set to Mandate and a sysadmin subscribes the instance to a policy category, all databases that meet the target set are controlled by the policies within the policy category. A policy subscription to a policy category set to Mandate cannot be overridden by a database owner.