As the output of the Layout Layer is an unrendered presentation, there must be a further component which takes this representation as input and converts it into a presentation perceivable by the user. This part of a presentation system is often called ``presentation display component'' or ``presentation runtime environment''. The Presentation Display Layer (cf. Fig. 10) of the RM captures the functionalities of such components. An Output Coordination component dispatches each part of the unrendered presentation to the interface of a suitable media-specific Display Module. In the RM a Display Module serves as an abstract reference to any of the devices which can be used for the display of a media object of a certain type.
In Fig. 10 the arrows starting from the
Display Device components are merged to illustrate the fact that the
result presented to the user is the (spatially and temporally)
coordinated fusion of these outputs. Note that solving this task may
require intelligent decision making, because resource limitations
must be taken into account. Therefore, the Presentation Display Layer
has also access to the RM's Knowledge Server.
As reference models for multimedia runtime environments are currently under development, there is no need to repeat this work here. Rather the strategy is to refine the Presentation Display Layer with appropriate concepts from emerging standards such as PREMO.
