4.0 likes s and S protections

[Jon_J._Brewster%Wayne-MTS at um.cc.umich.edu]

The setgid permission on directories under 4.0 controls the group
ownership of files created within the directories.  If the setgid bit is
set, the created file inherits the group ownership of the containing
directory.  If it is not set, the file inherits the group ownership of the
creating process.  I.e., with the bit set, it works the way 3.X did...
It's documented in the man page for chmod, as well as in the release
notes.

[[ My thanks to others who have also pointed this out.  This is fully
explained in the 4.0 Change Notes, section 2.4 (I'm going to have to put a
copy next to my Sun when I do Sun-Spots from now on).  By the way, I
understand that the default semantics (those used without the set group-id
bit on) are SVID semantics.  To remove a set-gid bit with chmod, one
cannot merely "chmod 700".  One must use "chmod g-s".  --wnl ]]