This project is based upon the parallel caase example from:

R.J. Leduc.  Hierarchical Interface-based Supervisory
Control. Doctoral Thesis, Dept. of Elec. & Comp. Engrg., Univ. of
Toronto, 2002.  

http://www.cas.mcmaster.ca/~leduc/

- it has been extended to be a multi-level example and to use low-data
  events. 