Enhancing the SysLab System Model with State
  In this report, the SYSLAB model is complemented in different ways: State-box models are provided through timed port automata, for which an operational and a corresponding denotational semantics are given. Composition is defined for components modeled in the state-box view as well as for components modeled in the black-box view. This composition is well-defined for networks of infinitely many components. To show the applicability of the model, several examples are given. 
Radu Grosu, Cornel Klein, Bernhard Rumpe
cs.SE