A CalendarPeriod represents the abstract concept of a time
period that has a canonical start. All calendar times begin at 12 AM
US and Canadian Pacific Time (UTC-8).
Values:
CALENDAR_PERIOD_UNSPECIFIED (0):
Unspecified.
MONTH (1):
The month starts on the first date of the
month and resets at the beginning of each month.
QUARTER (2):
The quarter starts on dates January 1, April
1, July 1, and October 1 of each year and resets
at the beginning of the next quarter.
YEAR (3):
The year starts on January 1 and resets at
the beginning of the next year.
WEEK (4):
The week period starts and resets every
Monday.
DAY (5):
The day starts at 12:00am.
