Aliases for day numbers, where ``MONDAY`` is ``0`` and ``SUNDAY`` is ``6``.
+
+The :mod:`calendar` module defines the following exceptions:
+
+.. exception:: IllegalMonthError(month)
+
+ A subclass of :exc:`ValueError`,
+ raised when the given month number is outside of the range 1-12 (inclusive).
+
+ .. attribute:: month
+
+ The invalid month number.
+
+
+.. exception:: IllegalWeekdayError(weekday)
+
+ A subclass of :exc:`ValueError`,
+ raised when the given weekday number is outside of the range 0-6 (inclusive).
+
+ .. attribute:: weekday
+
+ The invalid weekday number.
+
+
.. seealso::
Module :mod:`datetime`