The UML does not have good intrinsic support for:

  • Deeply nested structures.
  • Physical, industrial, and financial quantities with units.
  • Physical flows.
  • Representation of deep value state and modes of instances of complex systems.
  • Mathematical constraints analysis.
  • Progressive refinement of systems models through allocation.

For many years some engineers and scientists like Dr Darren have experimented (and often struggled) with re-appropriation of UML™ for modelling and engineering of complex systems and heterogeneous systems that combine software-like elements with physical systems and systems engineering models.

The UML is however highly extensible.