Obtaining Access to Restricted Features
Under normal circumstances, developers can create applications that use basic methods and properties to produce innovative applications. More demanding applications may require advanced features like ActiveX® controls, interacting with the MSN® Messenger Chat History window, or getting information from a user's Microsoft® .NET Passport. Implementing these features requires access to a set of methods and properties that are available only to applications with special permissions granted by Microsoft.
For more information on the permissions that can be obtained, see Permission Flags.