This page describes special circumstances and limitations related to date field values in ORA.
ORA's date-related transforms support dates from 1 January 0001 to dates well into the future. ORA's date manipulation transforms do not support BCE (BC) dates.
ORA does not attempt to detect which calendar was used to record a date. It's up to the user to decide based on the collection, time-period, etc.
Records in a single collection may include dates from one or more calendars.
Julian to Gregorian Conversion
ORA's dateJtoG and dateGtoJ transforms will convert any Julian date within the supported date range to or from its Gregorian equivalent. However, converting dates is still an error-prone process. While the conversion steps are relatively simple, you must know the effective date range for Julian dates and the first day of the new year that was in effect when the date was recorded. Determining those values depends on several factors.
- Locale: A Julian date recorded in one locale in one era may have used a different "New Year's Day" than a Julian date recorded in a difference locale or era.
For example, in England in 1556, the new year began on March 25, although civil, liturgical, and tax calendars in England may not have all used the same "New Year's Day". Meanwhile, in Spain in 1556, the new year began on January 1.
In some cases, different regions of the same country changed calendars at different times. For example, most Roman Cathloc areas of Switzerland converted to the Gregorian calendar in 1584, but most Protestant areas in Switzerland converted in the 1700s.
- Organization: Within a locale, different organizations may have used different calendars.
For example, a church may have used a different calendar than a civil authority.
- Person: The person who recorded the date may or may not have been using the most-current calendar, especially around the time of a calendar change when notifications may or may not have been communicated effectively to all parties.
New Year's Day
After switching to the Gregorian calendar, most countries standardized on January 1 as the first day of the new year. The first day of the new year was not as uniform for countries and organizations using the Julian calendar. For example, from 1087 to 1155 the English year began on 1 January and from 1155 to 1751 it began on March 25.
To make matters more confusing, during the Middle Ages January 1 was often called "New Year's Day", but the year number was not necessarily incremented on that day.
When ORA converts a date to or from the Julian calendar, it combines the Julian 1st Month and Julian 1st Day properties to create the Julian New Year's Day, the day when the year number is incremented. If the Julian 1st Month and Julian 1st Day properties do not match the New Year's Day for the current record, the conversion result will not be correct for some days of the year. You may want to change the preferences or use the dateJNYD transform to temporarily change the Julian New Year's Day for the subsequent transforms in the current template.