Pthreads were first defined in the POSIX.1c standard (Threads extensions, IEEE Std 1003.1c-1995) from 1995 as an extension to the POSIX standard. At the time, UNIX had been chosen as a manufacturer-neutral interface, with POSIX unifying the various APIs among them.
Despite this standardization effort, differences still exist in Pthread implementations between OS's which implement it (for example, between Linux and OS X), courtesy of non-portable extensions (marked with _np in the method name).
For the pthread_setname_np method, the Linux implementation takes two parameters, allowing one to set the name of a thread other than the current thread. On OS X (since 10.6), this method only takes one parameter, allowing one to set the name of the current thread only. If portability is a concern, one has to be mindful of such differences.
After 1997, the POSIX standard...
