This is a linked open data (LOD) about date and time. "C.E. 2013 May 01" is a date of Julian/Gregorian Calendar (reformed in 1752) (Calendar ID: 101.2).
http://datetime.hutime.org/calendar/101.2/date/C.E._2013_May_01
hcal:101.2/date/2456413.5
hcal:101.2/date/C.E._2013_May_01
hcaldate:2456413.5
hcaldate:C.E._2013_May_01