This is a linked open data (LOD) about date and time. "C.E. 2020 December 31" is a date of Julian Calendar (Calendar ID: 102.1).
http://datetime.hutime.org/calendar/102.1/date/C.E._2020_December_31
hcal:102.1/date/2459227.5
hcal:102.1/date/C.E._2020_December_31
hcaldate:2459227.5
hcaldate:C.E._2020_December_31