Presentation services is the component of the client/server execution architecture that controls how users interact with the system. If the user requires a style or form of interaction with an application, the presentation services layer has a function that prescribes how that interaction should be implemented. Netcentric applications typically are in the Pseudo to Standard graphical user interface range of the Interface Continuum depending on their use of Hypertext Markup Language forms or Java applets. Once a appropriate metaphor has been defined for the application being designed, interaction styles must be chosen for performing the various activities and functions within the application. Netcentric applications are similar, but the functions of the Operating System, Window Manager, and Windowing Library are effectively combined and handled by the browser. Direct Manipulation Services enable applications to provide a direct manipulation interface. A direct manipulation interface allows users to manage multiple “application objects” by manipulating visual representations of those objects.