java/time/Period.java

250      * If the amount is a {@code ChronoPeriod} then it must use the ISO chronology.
263                 throw new DateTimeException("Period requires ISO chronology: " + amount);
463      * Gets the chronology of this period, which is the ISO calendar system.
470      * @return the ISO chronology, not null
622      * @throws DateTimeException if the specified amount has a non-ISO chronology or
711      * @throws DateTimeException if the specified amount has a non-ISO chronology or
864      * If the temporal has a chronology, it must be the ISO chronology.
875      * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
917      * If the temporal has a chronology, it must be the ISO chronology.
928      * First, the chronology of the temporal is checked to ensure it is ISO chronology or null.
966      * Validates that the temporal has the correct chronology.
970         Chronology temporalChrono = temporal.query(TemporalQueries.chronology());