[This is preliminary documentation and is subject to change.]
Returns whether the day-of-week field refers to ISO days. If true, types such as LocalDateTime
can use the IsoDayOfWeek property to avoid using magic numbers.
This defaults to true, but can be overridden by specific calendars.

Assembly: NodaTime (Module: NodaTime.dll) Version: 1.2.0.0 (1.2.0)