-EVENT should be a click, drag, or key press event.
-If it is a key press event, the return value has the form
- (WINDOW POS (0 . 0) 0)
-If it is a click or drag event, it has the form
- (WINDOW AREA-OR-POS (X . Y) TIMESTAMP OBJECT POS (COL . ROW)
- IMAGE (DX . DY) (WIDTH . HEIGHT))
-The `posn-' functions access elements of such lists.
-For more information, see Info node `(elisp)Click Events'.
-
-If EVENT is a mouse or key press or a mouse click, this is the
-position of the event. If EVENT is a drag, this is the starting
-position of the drag."
+EVENT should be a mouse click, drag, or key press event. If
+EVENT is nil, the value of `posn-at-point' is used instead.
+
+The following accessor functions are used to access the elements
+of the position:
+
+`posn-window': The window the event is in.
+`posn-area': A symbol identifying the area the event occurred in,
+or nil if the event occurred in the text area.
+`posn-point': The buffer position of the event.
+`posn-x-y': The pixel-based coordinates of the event.
+`posn-col-row': The estimated column and row corresponding to the
+position of the event.
+`posn-actual-col-row': The actual column and row corresponding to the
+position of the event.
+`posn-string': The string object of the event, which is either
+nil or (STRING . POSITION)'.
+`posn-image': The image object of the event, if any.
+`posn-object': The image or string object of the event, if any.
+`posn-timestamp': The time the event occurred, in milliseconds.
+
+For more information, see Info node `(elisp)Click Events'."