EDTF Field

Introduction

In version 21.3 we introduce a new field (definition) type EDTFField whose content corresponds with the metadata standard EDTF specifically for the fully supported levels 0 and 1. Since 23.1, level 2 COMPLETELY_UNSPECIFIED is also supported. The validity of these dates is checked both in front-ends and APIs. Each EDTF date corresponds with an interval, for example 2021-04-XX corresponds to the entire month of April 2021.

Indexation

Each EDTF date corresponds with an interval in time. An EDTF field can be searched as follows

By specifying a point in time → +MyDateField:"1985-04-01T00:00:00"
- Will search for all dates on the April 1st 1985 at midnight
By specifying a date range → +MyDateField:[1985-04-01 TO 1986-23]
- Will search for all dates from April 1st 1985 until the end of Autumn 1986.
By specifying an EDTF date → +MyDateField:"2014/2015-06"
- Will search for all dates from the start of 2014 until the end of June 2015.
Literal or textual searches on EDTF dates are not supported
- e.g. +MyDateField:20*
- +MyDateField:2014 matches not only with 2014 but also with 2014-XX, 2014-03-25T12:32:15, 2010/2030 etc

Overview

The tables below shows the supported EDTF features. The interval associated with the EDTF date, does not include the end, which technically means it is half open: [Left,Right[

Level 0

Name	Example	Left	Right (open)

Name	Example	Left	Right (open)
`DATE_COMPLETE`	`1985-04-12`	`1985-04-12T00:00:00`	`1985-04-13T00:00:00`
`DATE_PRECISION_YEAR_AND_MONTH`	`1985-04`	`1985-04-01T00:00:00`	`1985-05-01T00:00:00`
`DATE_PRECISION_YEAR`	`1985`	`1985-01-01T00:00:00`	`1986-01-01T00:00:00`
`DATETIME_COMPLETE`	`1985-04-12T23:20:30`	`1985-04-12T23:20:30`	`1985-04-12T23:20:31`
`DATETIME_COMPLETE_UTC`	`1985-04-12T23:20:30Z`	`1985-04-12T23:20:30Z`	`1985-04-12T23:20:31Z`
`DATETIME_COMPLETE_SHIFT`	`1985-04-12T23:20:30+04:30`	`1985-04-12T23:20:30+04:30`	`1985-04-12T23:20:31+04:30`
`TIME_INTERVAL` 2 `DATE_*` separated by `/`	`1985-04/1986`	`1985-04-01T00:00:00`	`1987-01-01T00:00:00`

Level 1

Name	Sub Level	Example	Left	Right (open)

Name	Sub Level	Example	Left	Right (open)
`LETTER_PREFIXED_YEAR`		`Y170000002`	`170000002-01-01T00:00:00`	`170000003-01-01T00:00:00`
`SEASONS` The values 21, 22, 23, 24 may be used used to signify Meteorological season Spring: 21 = 01/03 → 01/06 Summer: 22 = 01/06 → 01/09 Autumn: 23 = 01/09 → 01/12 Winter: 24 = 01/12 → 01/03		`1985-21`	`1985-03-01T00:00:00`	`1985-06-01T00:00:00`
`DATE_QUALIFICATION_UNCERTAIN` `DATE_*` plus `?`	`?` uncertain	`1985-04?`	`1985-04-01T00:00:00`	`1985-05-01T00:00:00`
`DATE_QUALIFICATION_APPROXIMATE` `DATE_*` plus `?`	`~` approximate	`1985-04~`	`1985-04-01T00:00:00`	`1985-05-01T00:00:00`
`DATE_QUALIFICATION_UNCERTAIN_APPROXIMATE` `DATE_*` plus `?`	`%` uncertain and approximate	`1985-04%`	`1985-04-01T00:00:00`	`1985-05-01T00:00:00`
`UNSPECIFIED_DIGIT_FROM_THE_RIGHT`	`DECADE`	`198X`	`1980-01-01T00:00:00`	`1990-01-01T00:00:00`
`UNSPECIFIED_DIGIT_FROM_THE_RIGHT`	`CENTURY`	`19XX`	`1900-01-01T00:00:00`	`2000-01-01T00:00:00`
`UNSPECIFIED_DIGIT_FROM_THE_RIGHT`	`MONTH`	`1985-XX`	`1985-01-01T00:00:00`	`1986-01-01T00:00:00`
`UNSPECIFIED_DIGIT_FROM_THE_RIGHT`	`DAY_IN_YEAR`	`1985-XX-XX`	`1985-01-01T00:00:00`	`1986-01-01T00:00:00`
`UNSPECIFIED_DIGIT_FROM_THE_RIGHT`	`DAY_IN_MONTH`	`1985-04-XX`	`1985-04-01T00:00:00`	`1985-05-01T00:00:00`
`EXTENDED_INTERVAL`	`OPEN_END`	`1985-04-12/..`	`1985-04-12T00:00:00`	`*`
`EXTENDED_INTERVAL`	`OPEN_BEGIN`	`../1985-04-12`	`*`	`1985-04-12T00:00:00`
`EXTENDED_INTERVAL`	`UNKNOWN_END`	`1985-04-12/`	`1985-04-12T00:00:00`	`*`
`EXTENDED_INTERVAL`	`UNKNOWN_BEGIN`	`/1985-04-12`	`*`	`1985-04-12T00:00:00`
`EXTENDED_INTERVAL` with 1 or 2 of the dates being a `DATE_QUALIFICATION`		`1985-04%/1986`	`1985-04-01T00:00:00`	`1986-01-01T00:00:00`
`NEGATIVE_CALENDER_YEAR`		`-0750`	`-0750-01-01T00:00:00`	`-0749-01-01T00:00:00`

Level 2 (future release, >= 23.1)

Name	Sub Level	Example	Left	Right

Name	Sub Level	Example	Left	Right
`UNSPECIFIED`	`EONS`	`XXXX-04` `X750-03-1X`	`0001-04-01T00:00:00` `0750-03-10T00:00:00`	`9999-04-01T00:00:00` `9750-03-20T00:00:00`
`UNSPECIFIED`	`MILLENIUM`	`1XXX-04` `1XXX-08-XX`	`1000-04-01T00:00:00` `1000-08-01T00:00:00`	`1999-05-01T00:00:00` `1999-09-01T00:00:00`
`UNSPECIFIED`	`CENTURY`	`18XX-07` `18XX-07-X3`	`1800-07-01T00:00:00` `1800-07-03T00:00:00`	`1899-08-01T00:00:00` `1899-07-24T00:00:00`
`UNSPECIFIED`	`DECADE`	`181X-07` `181X-07-X3`	`1810-07-01T00:00:00` `1810-07-03T00:00:00`	`1819-08-01T00:00:00` `1819-07-24T00:00:00`
`UNSPECIFIED`	`YEAR`	`1812-X7` `1812-XX-X3`	`1812-07-01T00:00:00` `1812-01-03T00:00:00`	`1812-08-01T00:00:00` `1812-12-24T00:00:00`
`UNSPECIFIED`	`SEMESTERS`	`1812-1X` `1812-0X-X3`	`1812-10-01T00:00:00` `1812-01-03T00:00:00`	`1813-01-01T00:00:00` `1812-09-24T00:00:00`
`UNSPECIFIED`	`MONTH`	`1812-02-X2` `1812-02-X9`	`1812-02-01T00:00:00` `1812-02-01T00:00:00`	`1812-03-01T00:00:00` `1812-03-01T00:00:00`
`UNSPECIFIED`	`SUB_MONTH`	`1812-02-2X` `1812-02-1X`	`1812-02-20T00:00:00` `1812-02-10T00:00:00`	`1812-03-01T00:00:00` `1812-02-20T00:00:00`
`COMPLETELY_UNSPECIFIED` (since `23.1`)		`XXXX-XX-XX`	`0001-01-01T00:00:00`	`10000-01-01T00:00:00`

Notes

For INTERVAL and EXTENDED_INTERNAL the following rule applies START.left <= END.left
When no time zone is specified the time zone of the installation is used, which is the Brussels time zone.
INTERVAL only allows for DATE_* not for DATETIME_*
Note that year must have at least 4 digits, e.g. -750 is not allowed
Due to limitations of the underlying search engine, searching on negative years is not possible
Indexed searching on a range of intervals, e.g. XXXX-12-XX (every December during 10000 years), is technically not possible, hence the range simplified to the interval determined by the left-most X (e.g. X123 = 10000 years, 1X34 = 1000 years, 15X9 = 100 years, etc).