The core of the Date-Time API is the java.time package. The classes defined in java.time base their calendar system on the ISO calendar, which is the world standard for representing date and time. The ISO calendar follows the proleptic Gregorian rules. There are also non-ISO calendars predefined in java.time.chrono package: the Japanese, Hijrah, Minguo, and Thai Buddhist calendars. For more about the Date-Time API, see the Internationalization Trail in the Java Tutorials.