The description of NonISOCalendarDateToISO AO states that the AO constrains an invalid date as well as RegulateISODate. While a month code and a day are constrained in the AO, I couldn't find a step which constrains an ordinal month (fields.[[month]]). Is this a spec bug, or did I overlook something?

https://tc39.es/proposal-intl-era-monthcode/#sup-temporal-nonisocalendardatetoiso

Note that all existing implementations clamp (when 'constrain') or reject (when 'reject') an out-of-range ordinal month:

// V8 and SpiderMonkey
Temporal.PlainDate.from({ year: 1, month: 14, day: 1, calendar: 'coptic' }).month; // 13
Temporal.PlainDate.from({ year: 1, month: 14, day: 1, calendar: 'coptic' }, { overflow: 'reject' }); // RangeError