A critical category for SEs would be exemplars of successful implementations of the SPT theoretical knowledge base to solving practical engineering problems. It is also the most difficult to fulfill as the theoretical knowledge is just now becoming available in the detail needed to try significant application. Perhaps the best opportunity to collect exemplars on application would come from SE students using SPT in their thesis research. We could use the example of feedback as an initial example. It has a widespread, proven history of use in engineering across virtually every one of its domains. Another is the modularity characteristic of hierarchical structures. We argue that the 300 case studies cited above are also cases of SPs & LPs used by nature to solve critical systems problems.