Schema for the represenation of annually-recurring dates. Copyright 2006 Alan L. Lovejoy. All rights reserved. Abstract class for partial dates that do not specify any particular year. An annual date is usually used to represent a rule for annually-recurring dates, such as birthdays, holidays and DST transition dates. A particular day of the year, specified as an ordinal number--a partial date that specifies no particular year. Typically used as a partial date that recurs on the same day of the year each year. If the value of the dayOfYear element is equal to or less than zero, it indicates the number of days before the last day of the year. The specified day-of-year includes any leap days that may be present. A particular month of the year, without specifying any particular year. Typically used as a partial date that recurs on the same month of the year each year. The month is specified by the "month" element, whose type is chronos:MonthRef, which means that the "month" element may contain either a sublemenent named "ordinal" whose value is an ordinal month number, or else a subelement named "key" whose value is an enumeratation constant (an xsd:token) that semantically idenfifies a particular month (e.g., March (Gregorian/Julian) or Adar Rishon (Hebrew.)) If the subelement of "month" is "ordinal," and its value is equal to or less than zero, it indicates the number of months before the last month of the year. The specified month.ordinal includes any leap months that may be present. A particular day of a particular month of the year, without specifying any particular year. Typically used as a partial date to specify a date that recurs on the same date each year. Used to represent a date that annually recurs on the same day of the week within a seven-day period bounded by a specified month and day of the month. For example, to represent the recurrence rule for the US Thanksgiving holiday (which modernly occurs on the fourth Thursday in November,) the value of the "calendar" element would be set to Gregorian, the value of the month.ordinal element would be set to "11" (or alternatively, the value of the month.key element could be set to November--see chronos:MonthRef for more info) the value of the "minDayOfMonth" element would be set to 22 (indicating the seven-day period from the 22nd through the 28th of the month,) and the value of the dayOfWeek.ordinal elemement would be set to 5 (or alternatively, the value of the dayOfWeek.key element could be set to Thursday.) If the value of the "minDayOfMonth" element is less than or equal to zero, it indicates the number of days before the last day of the month. To represent the old rule for Thanskgiving (the last Thursday of November,) the value of the "minDayOfMonth" element could be set to either 24 or -6. The "daysOffset" element indicates the number of days that should be added to the date specified by all the other element values. So to represent the "day after Thanksgiving," set the element value as specified in the discussion above, and set the value of the "daysOffset" element to 1. Used to represent a date that annually recurs, but whose date of each occurrence each year must be computed by an algorithm. Easter is the canonical example of such an annually-recurring date. The "daysOffset" element indicates the number of days that should be added to the date represented by the element. For example, to represent "Good Friday," set the value of the "daysOffset" subelement of a GregorianEaster instance to -2. An instance represents the date on which Easter occurs in an unspecified year (which usually means any year of interest.) The semantics is specific to the rule for the ocurrence of Easter as specified in the Gregorian Calendar (the rule established by Pope Gregory; adopting a new rule for the occurrence of Easter so that it's occurrence dates would stay fixed relative to the seasons was the whole point behind switching from the Julian to the Gregorian Calendar in the first place.) An instance represents the date on which Easter occurs in an unspecified year (which usually means any year interest.) The semantics is specific to the rule for the ocurrence of Easter as specified inthe Julian Calendar (the original Dionysian rule from the monk who first suggested using the year of Christ's birth as the epoch year of the Julian Calendar.)