How are the system development and integration procedure separated for Integrated Modular Avionics? I'm reading this paper about IMA (Integrated Modular Avionics) and I don't get the splitting of the development and integration procedure. In page 4 it says:


  Airbus has to modify the conventional development processes and responsibilities. The IMA system development and integration procedure is split between
  
  
  the Avionic Module Supplier
  the Aircraft System Manufacturer
  Airbus
  


Who is the Aircraft System Manufacturer? Which is its function?

My doubt is principally about this paragraph that is few lines later:


  The open IMA concept puts the assembler into the position of the IMA system integrator. The
  development responsibility for the single systems and their functions remains at the system
  manufacturers. The avionic module supplier provides “empty” IMA modules to both, the
  system manufacturers and to assembler. The system manufacturer applies the CPIOM for the
  local function implementation and qualification. The assembler, in turn integrates the own
  empty CPIOM with the ADCN on the aircraft in order to establish the basic computing resource
  for different system functions.
The Aircraft System Manufacturer is the company developing the system that is being implemented on IMA hardware (supplied by the Avionic Module Supplier). They will likely develop software to load onto the IMA hardware to perform certain functions.

For example:
Airbus would like to implement a Thrust Reverser Control System for their new airplane. The system would take in some parameters gathered from various sensors within the aircraft, perform the necessary logic and/or calculations, and then provide the necessary control commands to the thrust reversers.

Now Airbus doesn't want to develop this specific system, so they contract it out to another company ACME Avionics. They provide ACME with the System Requirements Data, which describes how the system must operate, what inputs it will use, the Design Assurance Level of the system, and the IMA modules the system must use to implement the requirements.