OptionalNowThe clock. Defaults to the current time.
OptionalTimeIANA time zone the date tokens are worked out in. Defaults to 'UTC'.
OptionalUserThe context user. Required by the user tokens. UserInfo fits.
OptionalWeekFirst day of the week for Context.StartOfWeek: 1 = Monday (default, ISO 8601), 0 = Sunday.
What a token is worked out from.