正朔

正朔	zhēng shuò	first day of the first lunar month / (old) calendar promulgated by the first emperor of a dynasty
正	zhēng	first month of the lunar year
正	zhèng	straight / upright / proper / main / principal / to correct / to rectify / exactly / just (at that time) / right (in that place) / (math.) positive
朔	shuò	beginning / first day of lunar month / north