Δαφνη Ευτυχια Αρθουρος

"I doubt the [ISO] description of the average duration of the Calendar Year.

"ISO 8601:2004 2.2.13 has 'calendar year   cyclic time interval in a calendar which is required for one revolution of the Earth around the Sun and approximated to an integer number of calendar days'. ISO 8601:2000 3.30 had similar wording.

"Taken literally, that revolution can only be with respect to the 'Fixed Stars'. But the fundamental requirement on the Calendar Year from time immemorial is that it should be locked to the cycle of the four seasons; it is that which governs the provision of leap years. The seasons are caused by the tilt of the Earth's axis with respect to its orbital plane. The axis slowly precesses, and that is generally described by the Precession of the Eqinoxes; the period is about 25800 years. The difference is 39 ppm, about twice the Gregorian Correction."

-- Dr. J.R. Stockton, "Date and Time Formats"

"I doubt the [ISO] description of the average duration of the Calendar Year.

"ISO 8601:2004 2.2.13 has 'calendar year   cyclic time interval in a calendar which is required for one revolution of the Earth around the Sun and approximated to an integer number of calendar days'. ISO 8601:2000 3.30 had similar wording.

"Taken literally, that revolution can only be with respect to the 'Fixed Stars'. But the fundamental requirement on the Calendar Year from time immemorial is that it should be locked to the cycle of the four seasons; it is that which governs the provision of leap years. The seasons are caused by the tilt of the Earth's axis with respect to its orbital plane. The axis slowly precesses, and that is generally described by the Precession of the Eqinoxes; the period is about 25800 years. The difference is 39 ppm, about twice the Gregorian Correction."

-- Dr. J.R. Stockton, "Date and Time Formats"