This shows how the definition of EC++ can be made to encompass a variety of different Parallel C++ designs, without dictating exactly how a parallel version of C++ should be implemented on any specific architectures, or indeed limiting the scope of the standard by assuming any underlying architecture features. It is clear how any Parallel C++ could be made to conform to EC++ by maintaining the standard interfaces and standard libraries.
It could be that in some instantiations of an EC++ compliant Parallel C++ some of the sets of features (systems libraries, language extensions, language libraries) may appear as empty sets, (depending on the machine architecture at which the instantiation is aimed and the usage patterns which are envisaged for it) but if the overall architecture of EC++ is observed in the design of the instantiation then it can be shown that it is an EC++ compliant instantiation.
This model is further explained in diagram (Figure 1 ).