This templates computes for a given Gregorian date the ordinal date within the Gregorian year whose number is that of the current ISO year, extrapolated if the current date is not in that Gregorian year.
"{{orddate in gregyear of isoyear|2006|6|23}}" gives "174" [1]
"{{orddate in gregyear of isoyear|2006|1|1}}" gives "366" [2]
"{{orddate in gregyear of isoyear|2007|12|31}}" gives "0" [3]
