(Command-line option to suppress warning: -w-nst) 

In previous versions of the C++ specification, typedef and tag names declared inside classes were directly visible in the global scope. 

In the latest specification of C++, these names must be prefixed with class::qualifier if they are to be used outside of their class scope. 

The compiler issues this warning whenever a name is uniquely defined in a single class. The compiler permits this usage without class::. This allows older versions of code to compile.