Clarification for 7-3-1: extern "C++"

[anj]

For headers included by other C and C++ headers it is vital to use extern "C++".
But the rule implicitly forbids it by only allowing 3 kind of top level declarations.

Is it really intended to use this as the only compliant way:

Code:

extern "C"
{
  extern "C++"
  {
    namespace MY_API
    {
    }
  }
}