(event-modifiers, event-basic-type): Doc fixes.

1 files changed, 9 insertions, 2 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index 8282e3a9316..0572446aefc 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -644,7 +644,11 @@ The normal global definition of the character C-x indirects to this keymap.")
   "Return a list of symbols representing the modifier keys in event EVENT.
 The elements of the list may include `meta', `control',
 `shift', `hyper', `super', `alt', `click', `double', `triple', `drag',
-and `down'."
+and `down'.
+EVENT may be an event or an event type.  If EVENT is a symbol
+that has never been used in an event that has been read as input
+in the current Emacs session, then this function can return nil,
+even when EVENT actually has modifiers."
   (let ((type event))
     (if (listp type)
         (setq type (car type)))
@@ -671,7 +675,10 @@ and `down'."
 
 (defun event-basic-type (event)
   "Return the basic type of the given event (all modifiers removed).
-The value is a printing character (not upper case) or a symbol."
+The value is a printing character (not upper case) or a symbol.
+EVENT may be an event or an event type.  If EVENT is a symbol
+that has never been used in an event that has been read as input
+in the current Emacs session, then this function may return nil."
   (if (consp event)
       (setq event (car event)))
   (if (symbolp event)