document the flags O_ALT_IO and O_NOCTTY

lib/libc/sys/open.2

@@ -1,4 +1,4 @@
-.\"	$NetBSD: open.2,v 1.32 2003/08/07 16:44:03 agc Exp $
+.\"	$NetBSD: open.2,v 1.33 2005/08/11 10:35:24 pooka Exp $
 .\"
 .\" Copyright (c) 1980, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -29,7 +29,7 @@
 .\"
 .\"     @(#)open.2	8.2 (Berkeley) 11/16/93
 .\"
-.Dd May 8, 2003
+.Dd August 11, 2005
 .Dt OPEN 2
 .Os
 .Sh NAME
@@ -117,6 +117,18 @@ with
 .Dv O_DSYNC
 only, or specifying it without any other synchronized I/O integrity
 completion flag set, has no further effect.
+.It O_ALT_IO
+Alternate I/O semantics will be used for read and write operations
+on the file descriptor.
+Alternate semantics are defined by the underlying layers and will not
+have any alternate effect in most cases.
+.It O_NOCTTY
+If the file is a terminal device, the opened device is not
+made the controlling terminal for the session.
+This flag has no effect on
+.Nx ,
+since the system defaults to the abovementioned behaviour.
+The flag is present only for standards conformance.
 .El
 .Pp
 Opening a file with