Complex sentence: The current formal usage of the Anno Mundi calender era is implemented based on the calculations of Maimonides in "Mishneh Torah (Completed in AD 1178)," it is the official method of calculating years on the Hebrew Calendar currently in use.
Split into simpler sentences: The current formal usage of the Anno Mundi calender era is implemented based on the calculations of Maimonides in "Mishneh Torah (Completed in AD 1178)". It is the official method of calculating years on the Hebrew Calendar currently in use.