calendar era; year numbering system
Technical term used in historical and chronological contexts to refer to the system by which years are counted and named within a calendar.
Japan's calendar era system uses era names.
The Western calendar is a year numbering system based on the Christian era.
Compound of 紀年 (kinnen, 'chronology' or 'era') and 法 (hō, 'method' or 'system'). The exact historical derivation is uncertain, but the term is a modern technical coinage.