+Some platforms fail to detect trailing slash on non-directories, as in
+@code{chown("link-to-file/",uid,gid)}:
+FreeBSD 7.2, Solaris 9.
+@item
+Some platforms fail to update the change time when at least one
+argument was not -1, but no ownership changes resulted:
+OpenBSD 4.0.
+@item
+When passed an argument of -1, some implementations really set the owner