To sum things up a little, here are the different versions of the Single UNIX Specification, available from The Open Group:
SUSv2 (1997) http://www.opengroup.org/onlinepubs/7990989775/ SUSv3 (POSIX.1-2001/2004) http://www.opengroup.org/onlinepubs/009695399/ SUSv4 (POSIX.1-2008) http://www.opengroup.org/onlinepubs/9699919799/ -- David du Colombier
