In 2.3.3.1 Basic Char Syntax of Emacs Lisp Reference, I can not
understant the last sentence in parenthesis.

`\ ' is equal `space'. Why need an extra space after `\ ' to seperate
it from the following text.

Thanks


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/23.1/etc/DEBUG for instructions.


In GNU Emacs 23.1.1 (i686-pc-linux-gnu, GTK+ Version 2.16.1)
 of 2009-07-31 on laptop
Windowing system distributor `The X.Org Foundation', version 11.0.10503000
configured using `configure  '--prefix=/usr' '--build=i686-pc-linux-gnu'
'--host=i686-pc-linux-gnu' '--mandir=/usr/share/man'
'--infodir=/usr/share/info' '--datadir=/usr/share' '--sysconfdir=/etc'
'--localstatedir=/var/lib' '--program-suffix=-emacs-23'
'--infodir=/usr/share/info/emacs-23' '--with-sound' '--with-x'
'--without-toolkit-scroll-bars' '--with-gif' '--with-jpeg' '--with-png'
'--with-rsvg' '--with-tiff' '--with-xpm' '--with-xft' '--without-libotf'
'--without-m17n-flt' '--with-x-toolkit=gtk' '--without-hesiod'
'--without-kerberos' '--without-kerberos5' '--with-gpm' '--with-dbus'
'build_alias=i686-pc-linux-gnu' 'host_alias=i686-pc-linux-gnu' 'CFLAGS=-O2
-march=pentium-m -pipe' 'LDFLAGS=-Wl,-O1''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: en_US.UTF-8
  value of $LC_CTYPE: zh_CN.UTF-8
  value of $LC_MESSAGES: en_US.UTF-8
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=SCIM
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Info

Minor modes in effect:
  TeX-source-specials-mode: t
  show-paren-mode: t
  display-time-mode: t
  global-auto-complete-mode: t
  desktop-save-mode: t
  yas/minor-mode: t
  auto-image-file-mode: t
  shell-dirtrack-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Recent input:
<help-echo> <down-mouse-1> <mouse-2> <down-mouse-5>
<mouse-5> <down-mouse-4> <mouse-4> <down-mouse-1> <mouse-movement>
<mouse-movement> <drag-mouse-1> <down-mouse-1> <mouse-1>
<help-echo> <help-echo> <help-echo> <help-echo> <down-mouse-1>
<help-echo> <mouse-1> <help-echo> <help-echo> <down-mouse-5>
<mouse-5> <double-down-mouse-5> <double-mouse-5> <down-mouse-4>
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<help-echo> <down-mouse-1> <mouse-movement> <mouse-1>
<double-down-mouse-1> <double-mouse-1> <help-echo>
<help-echo> <help-echo> <down-mouse-1> <mouse-1> <down-mouse-1>
<mouse-1> <double-down-mouse-1> <double-mouse-1> <down-mouse-5>
<mouse-5> <help-echo> <down-mouse-1> <mouse-1> <help-echo>
<down-mouse-1> <mouse-2> <down-mouse-5> <mouse-5> <double-down-mouse-5>
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5>
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5>
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5>
<down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <help-echo> <help-echo> <help-echo>
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo>
<help-echo> <down-mouse-4> <mouse-4> <double-down-mouse-4>
<double-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <down-mouse-5>
<mouse-5> <double-down-mouse-5> <double-mouse-5> <triple-down-mouse-5>
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5>
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5>
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5>
<down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <help-echo> <help-echo> <help-echo>
<help-echo> <help-echo> <help-echo> <help-echo> l <down-mouse-4>
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <down-mouse-5> <mouse-5> <help-echo>
<down-mouse-1> <mouse-2> <down-mouse-5> <mouse-5> <double-down-mouse-5>
<double-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5>
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5>
<triple-down-mouse-5> <triple-mouse-5> <down-mouse-4>
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <help-echo>
<help-echo> <help-echo> l <help-echo> <down-mouse-1>
<help-echo> <mouse-movement> <mouse-1> <down-mouse-1>
<mouse-2> <down-mouse-5> <mouse-5> <double-down-mouse-5>
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5>
<down-mouse-5> <mouse-5> <double-down-mouse-5> <double-mouse-5>
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5>
<triple-mouse-5> <down-mouse-4> <mouse-4> <double-down-mouse-4>
<double-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4>
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4>
<triple-mouse-4> <help-echo> <down-mouse-1> <mouse-1>
<double-down-mouse-1> <double-mouse-1> <down-mouse-1>
<mouse-1> <down-mouse-1> <mouse-1> C-x C-e <down-mouse-1>
<mouse-1> <help-echo> <help-echo> C-x <help-echo> 2
<help-echo> <menu-bar> <buffer> C-g ? . C-x C-e <left>
\ C-x C-e <right> C-x C-e <help-echo> <down-mouse-1>
<mouse-1> C-x 1 <down-mouse-5> <mouse-5> <help-echo>
<help-echo> <down-mouse-5> <mouse-5> <down-mouse-5>
<mouse-5> <down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5>
<down-mouse-5> <mouse-5> <down-mouse-4> <mouse-4> <help-echo>
<down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5> <down-mouse-5>
<mouse-5> <down-mouse-4> <mouse-4> <help-echo> <help-echo>
<down-mouse-5> <mouse-5> <down-mouse-4> <mouse-4> <help-echo>
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo>
<menu-bar> <help-menu> <send-emacs-bug-report>

Recent messages:
byte-code: End of buffer [2 times]
bunzip2ing elisp-5.info.bz2...done
byte-code: End of buffer [3 times]
bunzip2ing elisp-1.info.bz2...done
bunzip2ing elisp-5.info.bz2...done
bunzip2ing elisp-1.info.bz2...done
byte-code: End of buffer
81
46
preceding-sexp: End of file during parsing
46