This is a linked open data (LOD) about date and time. "21 ניסן 5786" is a date of Hebrew Calendar-TEST (Calendar ID: 104.1).
http://datetime.hutime.org/calendar/104.1/date/21_ניסן_5786
hcal:104.1/date/2461138.5
hcal:104.1/date/21_ניסן_5786
hcaldate:2461138.5
hcaldate:21_ניסן_5786