-using two-character sequences starting with @key{ESC}. Thus, to enter
-@kbd{M-a}, you could type @kbd{@key{ESC} a}. To enter @kbd{C-M-a}, you
-would type @kbd{@key{ESC} C-a}. @key{ESC} is allowed on terminals with
-@key{META} keys, too, in case you have formed a habit of using it.
-
- X Windows provides several other modifier keys that can be applied to
-any input character. These are called @key{SUPER}, @key{HYPER} and
-@key{ALT}. We write @samp{s-}, @samp{H-} and @samp{A-} to say that a
-character uses these modifiers. Thus, @kbd{s-H-C-x} is short for
-@kbd{Super-Hyper-Control-x}. Not all X terminals actually provide keys
-for these modifier flags---in fact, many terminals have a key labeled
-@key{ALT} which is really a @key{META} key. The standard key bindings
-of Emacs do not include any characters with these modifiers. But you
-can assign them meanings of your own by customizing Emacs.
+using two-character sequences starting with @key{ESC}. Thus, you can
+enter @kbd{M-a} by typing @kbd{@key{ESC} a}. You can enter
+@kbd{C-M-a} by typing @kbd{@key{ESC} C-a}. Unlike @key{META}, which
+modifies other characters, @key{ESC} is a separate character. You
+don't hold down @key{ESC} while typing the next character; instead,
+you press it and release it, then you enter the next character.
+@key{ESC} is allowed on terminals with @key{META} keys, too, in case
+you have formed a habit of using it.
+
+ The X Window System provides several other modifier keys that can be
+applied to any input character. These are called @key{SUPER},
+@key{HYPER} and @key{ALT}. We write @samp{s-}, @samp{H-} and @samp{A-}
+to say that a character uses these modifiers. Thus, @kbd{s-H-C-x} is
+short for @kbd{Super-Hyper-Control-x}. Not all X terminals actually
+provide keys for these modifier flags---in fact, many terminals have a
+key labeled @key{ALT} which is really a @key{META} key. The standard
+key bindings of Emacs do not include any characters with these
+modifiers. But you can assign them meanings of your own by customizing
+Emacs.
+
+ If your keyboard lacks one of these modifier keys, you can enter it
+using @kbd{C-x @@}: @kbd{C-x @@ h} adds the ``hyper'' flag to the next
+character, @kbd{C-x @@ s} adds the ``super'' flag, and @kbd{C-x @@ a}
+adds the ``alt'' flag. For instance, @kbd{C-x @@ h C-a} is a way to
+enter @kbd{Hyper-Control-a}. (Unfortunately there is no way to add
+two modifiers by using @kbd{C-x @@} twice for the same character,
+because the first one goes to work on the @kbd{C-x}.)