Improve the description of the macros.

Patch from David H. Gutteridge in PR 24296.

usr.bin/ftp/ftp.1

@@ -1,6 +1,6 @@
-.\" 	$NetBSD: ftp.1,v 1.109 2005/02/20 20:54:01 wiz Exp $
+.\" 	$NetBSD: ftp.1,v 1.110 2005/07/05 09:29:54 lukem Exp $
 .\"
-.\" Copyright (c) 1996-2004 The NetBSD Foundation, Inc.
+.\" Copyright (c) 1996-2005 The NetBSD Foundation, Inc.
 .\" All rights reserved.
 .\"
 .\" This code is derived from software contributed to The NetBSD Foundation
@@ -64,7 +64,7 @@
 .\"
 .\"	@(#)ftp.1	8.3 (Berkeley) 10/9/94
 .\"
-.Dd January 15, 2005
+.Dd July 5, 2005
 .Dt FTP 1
 .Os
 .Sh NAME
@@ -668,7 +668,12 @@ in a file or
 carriage returns from the terminal) terminates macro input mode.
 There is a limit of 16 macros and 4096 total characters in all
 defined macros.
-Macros remain defined until a
+Macro names can be a maximum of 8 characters.
+Macros are only applicable to the current session they are
+defined within (or if defined outside a session, to the session
+invoked with the next
+.Ic open
+command), and remain defined until a
 .Ic close
 command is executed.
 The macro processor interprets `$' and `\e' as special characters.
@@ -2038,6 +2043,20 @@ next
 .Pa .netrc
 line and continue until a blank line (consecutive new-line
 characters) is encountered.
+Like the other tokens in the
+.Pa .netrc
+file, a
+.Ic macdef
+is applicable only to the
+.Ic machine
+definition preceding it.
+A
+.Ic macdef
+entry cannot be utilized by multiple
+.Ic machine
+definitions; rather, it must be defined following each
+.Ic machine
+it is intended to be used with.
 If a macro named
 .Ic init
 is defined, it is automatically executed as the last step in the