What is the use of feholdexcept etc.?

The documentation (in the standards) for all of fenv.h is rather confusing, but I'm especially confused about feholdexcept and the concept of "non-stop mode" for a floating point exception. As far as I can tell, on any IEEE floating point implementation, exceptions are non-signaling/"non-stop" by default, and the fenv.h interfaces seem to provide no way to enable a signaling mode unless it was the default. Is the whole concept of feholdexcept useless except on non-IEEE systems or systems with nonstandard extensions for setting the signaling exception mask?