Although not being an official calendar, in South Korea, the traditional Korean calendar is still maintained by the government. The current version is based on China's Shixian calendar (""shi-heon-nyeok" 시헌력 (時憲暦)" in Korean), which was in turn developed by Jesuit scholars. However, because the Korean calendar is now based on the moon's shape seen from Korea, occasionally the calendar diverges from the traditional Chinese calendar by one day, even though the underlying rule is the same. As a result, sometime the New Year's Day differ by one between the two countries, which last happened in 1997.