How to signify formatting with cyclic date elements?

[Kip Cole]

The date time format pattern codes, specifically “y”, “M” and “d” do not clarify when to use the cyclic name sets or the “standard” numeric name sets.  “U” can be used for the cyclic year.  For the Chinese, Korean Dangi and Japanese traditional calendars I’m unclear on whether these format codes are intended to always reflect their numeric values. Or if for cyclic calendars they are intended to be used for the cyclic names.

The “Month Patterns/Cyclic name sets” defines a hints for leap year formatting in lunisolar calendars, but no indication of when to use the numeric context versus the cyclic context.

My question therefore is:

1. Is it assumed that the cyclic names are used for `y`, `M` and `d` if the calendar has cyclic name data?
2. Is there typically an option set in ICU to determine which context to use? (I did google for hints on this in ICU documentation but couldn’t see anything)
3. Or is there some other data-drive mechanism I’m missing?

Thanks for the help,

—Kip