- add   where appropriate.

- add missing replaceable tags.

en_US.ISO8859-1/books/handbook/install/chapter.sgml

@@ -895,7 +895,7 @@ We can take no responsibility for lost disk contents!</literallayout>
 	    opportunity.</para>
 
 	  <note>
-	    <para>For &os; 7.3 and previous versions, installation
+	    <para>For &os;&nbsp;7.3 and previous versions, installation
 	      boot floppies are available and can be prepared as
 	      described in <xref linkend="install-boot-media">.  One of
 	      them will be the first boot disc:
@@ -3041,8 +3041,8 @@ Press [Enter] now to invoke an editor on /etc/exports
       <title>Linux Compatibility</title>
 
       <note>
-	<para>This part only applies to &os;&nbsp;7.X installation, if
+	<para>This part only applies to &os;&nbsp;7.<replaceable>X</replaceable> installation, if
-	  you install &os;&nbsp;8.X this screen will not be
+	  you install &os;&nbsp;8.<replaceable>X</replaceable> this screen will not be
 	  proposed.</para>
       </note>
 
@@ -4430,7 +4430,7 @@ Please press any key to reboot.</screen>
 
 	    <screen>&prompt.root; <userinput>cu -l /dev/cuau0</userinput></screen>
 
-	    <para>On &os; 7.X use the following command
+	    <para>On &os;&nbsp;7.<replaceable>X</replaceable> use the following command
 	      instead:</para>
 
 	    <screen>&prompt.root; <userinput>cu -l /dev/cuad0</userinput></screen>
@@ -4598,7 +4598,7 @@ Please press any key to reboot.</screen>
 	  </table>
 
 	  <note>
-	    <para>&os;&nbsp;7.X releases before &os;&nbsp;7.3 and
+	    <para>&os;&nbsp;7.<replaceable>X</replaceable> releases before &os;&nbsp;7.3 and
 	      &os;&nbsp;8.0 used a
 	      different naming convention.  The names of their ISO
 	      images are not prefixed with