This is a linked open data (LOD) about date and time. "28/11/1220" is a date of Hijri Calendar-TEST (Calendar ID: 9103.1).
http://datetime.hutime.org/calendar/9103.1/date/28/11/1220
hcal:9103.1/date/2380734.5
hcal:9103.1/date/28/11/1220
hcaldate:2380734.5
hcaldate:28/11/1220