In system design, generation of high-level abstract models that can be closely associated with evolving lower-level models provides designers with the ability to incrementally "test" an evolving design against a model of a specification. Such high-level models may deal with areas such as performance, reliability, availability, maintainability, and system safety. Abstract models also allow exploration of the hardware versus software design space in an incremental fashion as a fuller, detailed design unfolds, leaving behind the old practice of hardware-software binding too early in the design process. Such models may also allow the inclusion of non-functional aspects of design (e.g. space, power, heat) in a simulatable information model dealing with the system's operation. This text addresses model generation and application specifically in the following domains: specification modelling (linking object/data modelling, behaviour modelling, and activity modelling); operational specification modelling (modelling the way the system is supposed to operate - from a user's viewpoint); linking non-functional parameters with specification models; hybrid modelling (linking performance and functional elements); application of high-level modelling to hardware/software approaches; mathematical analysis techniques related to the modelling approaches; reliability modelling; and applications of high level modelling.