Export: Make validation link fully configurable

lisp/org-exp.el

@@ -749,7 +749,11 @@ This is customizable so that alignment options can be specified."
 (defcustom org-export-html-validation-link nil
   "Non-nil means, add validationlink to postamble of HTML exported files."
   :group 'org-export-html
-  :type 'boolean)
+  :type '(choice
+	  (const :tag "Nothing" nil)
+	  (const :tag "XHTML 1.0" "<p class=\"xhtml-validation\"><a href=\"http://validator.w3.org/check?uri=referer\">Validate XHTML 1.0</a></p>")
+	  (string :tag "Specify full HTML")))
+
 
 (defcustom org-export-html-with-timestamp nil
   "If non-nil, write `org-export-html-html-helper-timestamp'
@@ -4080,7 +4084,7 @@ lang=\"%s\" xml:lang=\"%s\">
 	    (insert (format "<p class=\"creator\">HTML generated by org-mode %s in emacs %s</p>\n"
 			    org-version emacs-major-version)))
 	  (when org-export-html-validation-link
-	    (insert "<p class=\"xhtml-validation\"><a href=\"http://validator.w3.org/check?uri=referer\" target=\"_blank\">Validate XHTML 1.0</a></p>"))
+	    (insert org-export-html-validation-link "\n"))
 	  (insert "</div>"))
 
 	(if org-export-html-with-timestamp