A date object represents a date in the Gregorian calendar and a time of day on that date in some timezone.
The fields are year, month, day, hour, minute, second, nanoseconds and timezone. A date object is immutable, its fields can be read but they cannot be modified once the object is created.
#t if obj is a date object, or
#f if not.
Create a new date object.
Nanoseconds, 0 to 999999999.
Seconds, 0 to 59, or 60 for a leap second. 60 is never seen when working entirely within UTC, it’s only when converting to or from TAI.
Minutes, 0 to 59.
Hour, 0 to 23.
Day of the month, 1 to 31 (or less, according to the month).
Month, 1 to 12.
Year, eg. 2003. Dates B.C. are negative, eg. -46 is 46 B.C. There is no year 0, year -1 is followed by year 1.
Time zone, an integer number of seconds east of Greenwich.
Day of the year, starting from 1 for 1st January.
Day of the week, starting from 0 for Sunday.
Week of the year, ignoring a first partial week. dstartw is the day of the week which is taken to start a week, 0 for Sunday, 1 for Monday, etc.
Return a date object representing the current date/time, in UTC offset by tz-offset. tz-offset is seconds east of Greenwich and defaults to the local timezone.
Return the current Julian Day.
Return the current Modified Julian Day.