(Window Systems): Document the value of `initial-window-system' under --daemon.

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index b29515cdc8f7a7f76b4e1e73932fdcb970e1a7d2..42423f8309f30972321ad5036255e93e3d3d58b3 100644 (file)
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -5784,7 +5784,10 @@ Emacs is displaying the frame on a character-based terminal.
 
 @defvar initial-window-system
 This variable holds the value of @code{window-system} used for the
-first frame created by Emacs during startup.
+first frame created by Emacs during startup.  (When Emacs is invoked
+with the @option{--daemon} option, it does not create any initial
+frames, so @code{initial-window-system} is @code{nil}.  @xref{Initial
+Options, daemon,, emacs, The GNU Emacs Manual}.)
 @end defvar
 
 @defun window-system &optional frame