If -u is specified or UTF-8 is otherwise detected when the server is started,

enable the utf8 and status-utf8 optons. While here, note in the man page that
the server is started with the first session and exits when none remain.

tmux.1

@@ -1,4 +1,4 @@
-.\" $Id: tmux.1,v 1.118 2009-07-17 18:32:54 tcunha Exp $
+.\" $Id: tmux.1,v 1.119 2009-07-18 11:05:13 nicm Exp $
 .\"
 .\" Copyright (c) 2007 Nicholas Marriott <nicm@users.sourceforge.net>
 .\"
@@ -36,11 +36,13 @@ controlled from a single terminal.
 .Pp
 .Nm
 runs as a server-client system.
-A server is created automatically when necessary and holds a number of
+A server holds a number of
 .Em sessions ,
 each of which may have a number of
 .Em windows
 linked to it.
+A server is started automatically when the first session is created and exits
+when all the sessions it contains are destroyed.
 A window may be split on screen into one or more
 .Em panes ,
 each of which is a separate terminal.
@@ -123,6 +125,14 @@ This is not always correct: the
 flag explicitly informs
 .Nm
 that UTF-8 is supported.
+.Pp
+If the server is started from a client passed
+.Fl u
+or where UTF-8 is detected, the
+.Ic utf8
+and
+.Ic status-utf8
+options are enabled in the global window and session options respectively.
 .It Fl v
 Request verbose logging.
 This option may be specified multiple times for increasing verbosity.