(defun list-holidays (y1 y2 &optional l label)
"Display holidays for years Y1 to Y2 (inclusive).
-The optional list of holidays L defaults to `calendar-holidays'. See the
-documentation for that variable for a description of holiday lists.
+The optional list of holidays L defaults to `calendar-holidays'.
+If you want to control what holidays are displayed, use a
+different list. For example,
+
+ (list-holidays 2006 2006
+ (append general-holidays local-holidays other-holidays))
+
+will display holidays for the year 2006 defined in the 3
+mentioned lists, and nothing else.
+
+When called interactively, this command offers a choice of
+holidays, based on the variables `solar-holidays' etc. See the
+documentation of `calendar-holidays' for a list of the variables
+that control the choices, as well as a description of the format
+of a holiday list.
The optional LABEL is used to label the buffer created."
(interactive