PATCH: Missing keywords in defcustom documentation

[Per Abrahamsen]

The doc string for defcustom doesn't mention :link, :tag and :load.
This is particularly sad for :link, which I think has the potential
for being very useful, but sadly is used far too little.

Here is a patch to add them (text taken from the elisp manual):

2002-01-03  Per Abrahamsen  <abraham@dina.kvl.dk>

        * custom.el (defcustom): Documented :tag, :link and :load.

Index: lisp/custom.el
===================================================================
RCS file: /cvsroot/emacs//emacs/lisp/custom.el,v
retrieving revision 1.47
diff -c -r1.47 custom.el
*** lisp/custom.el      4 Dec 2001 21:24:17 -0000       1.47
--- lisp/custom.el      3 Jan 2002 12:40:17 -0000
***************
*** 1,6 ****
  ;;; custom.el --- tools for declaring and initializing options
  ;;
! ;; Copyright (C) 1996, 1997, 1999, 2001 Free Software Foundation, Inc.
  ;;
  ;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
  ;; Maintainer: FSF
--- 1,6 ----
  ;;; custom.el --- tools for declaring and initializing options
  ;;
! ;; Copyright (C) 1996, 1997, 1999, 2001, 2002 Free Software Foundation, Inc.
  ;;
  ;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
  ;; Maintainer: FSF
***************
*** 173,178 ****
--- 173,205 ----
  :options VALUE should be a list of valid members of the widget type.
  :group  VALUE should be a customization group.
          Add SYMBOL to that group.
+ :link LINK-DATA'
+         Include an external link after the documentation string for this
+         item.  This is a sentence containing an active field which
+         references some other documentation.
+    
+         There are three alternatives you can use for LINK-DATA:
+    
+         `(custom-manual INFO-NODE)'
+              Link to an Info node; INFO-NODE is a string which specifies
+              the node name, as in `\"(emacs)Top\"'.  The link appears as
+              `[manual]' in the customization buffer.
+    
+         `(info-link INFO-NODE)'
+              Like `custom-manual' except that the link appears in the
+              customization buffer with the Info node name.
+    
+         `(url-link URL)'
+              Link to a web page; URL is a string which specifies the URL.
+              The link appears in the customization buffer as URL.
+    
+         You can specify the text to use in the customization buffer by
+         adding `:tag NAME' after the first element of the LINK-DATA; for
+         example, `(info-link :tag \"foo\" \"(emacs)Top\")' makes a link to the
+         Emacs manual which appears in the buffer as `foo'.
+    
+         An item can have more than one external link; however, most items
+         have none at all.
  :initialize
        VALUE should be a function used to initialize the
        variable.  It takes two arguments, the symbol and value
***************
*** 193,198 ****
--- 220,232 ----
          VALUE should be a string specifying that the variable was
          first introduced, or its default value was changed, in Emacs
          version VERSION.
+ :tag LABEL
+         Use LABEL, a string, instead of the item's name, to label the item
+         a  in customization menus and buffers.
+ :load FILE
+         Load file FILE (a string) before displaying this customization
+         item.  Loading is done with `load-library', and only if the file is
+         not already loaded.
  :set-after VARIABLE
        Specifies that SYMBOL should be set after VARIABLE when
        both have been customized.