calendar-read-date
calendar-read-date is a compiled Lisp function in `calendar.el
'.
(calendar-read-date &optional NODAY)
Prompt for Gregorian date. Return a list (month day year).
If optional NODAY is t, does not ask for day, but just returns
(month 1 year); if NODAY is any other non-nil value the value returned is
(month year)