I just watched a video course by Paul Randall on performance tuning with wait stats (highly recommended course!) and he said that if you remove the PREEMPTIVE_OS_ you are left with the windows api name. so in this case GETPROCADDRESS - a quick google search gives more information on the API. http://msdn.microsoft.com/en-us/library/windows/desktop/ms683212%28v=vs.85%29.aspx