Commons:Structured data/Modeling/Date

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How to model various types of times and dates in structured data, for files on Wikimedia Commons Wikidata has many properties related to time, all listed in d:Wikidata:List of properties/time, and many might be relevant to Commons. The most relevant property is inception (P571) to be used for storing the time

• photograph was taken,
• document created,
• painting or other artwork completed.

Storing of imprecise dates

Sometimes dates like date of creation of some artwork are not precisely known. On Commons we traditionally used {{Other date}} and {{Complex date}} templates for that. On SDC we will use qualifiers developed on Wikidata and described in Help:Dates. Below is a copy of most relevant section.

Qualifiers can be used to explain or customize dates that cannot be fully represented in YYYY-MM-DD, YYY-MM or YYYY formats. The precision of the date being qualified should have a precision that encompasses the range described by the qualifiers, or be set to "unknown value" (["snaktype"] = "somevalue").

• earliest date (P1319) and/or latest date (P1326) - earliest and latest possible time that some event could have occurred.
• start time (P580) and/or end time (P582) - beginning and end of some period of time.
• sourcing circumstances (P1480) qualification of the accuracy of a statement. Allowed values: circa (Q5727902), near (Q21818619), presumably (Q18122778), disputed (Q18912752), etc.

• refine date (P4241) qualifier to narrow down the precision of a date. Allowed values:

• parts, like beginning of (Q40719727), middle of (Q40719748) and end of (Q40719766)
• halves, usually of a year, decade or century first half (Q40719687) and second half (Q40719707)
• quarters, usually of a century: first quarter (Q40690303), second quarter (Q40719649), third quarter (Q40719662) and fourth quarter (Q40719674)
• seasons, observed in northern and southern hemisphere

• winter (northern hemisphere) (Q40720553), spring (northern hemisphere) (Q40720559), summer (northern hemisphere) (Q40720564), autumn (northern hemisphere) (Q40720568)
• winter (southern hemisphere) (Q40720946), spring (southern hemisphere) (Q40720950), summer (southern hemisphere) (Q40720953), autumn (southern hemisphere) (Q40720956)

Example dates and how to save them

statement	code	Example from
circa 500 BCE	500 BCE / sourcing circumstances (P1480) circa (Q5727902)	Pythagoras (Q10261) date of death (P570)
after 741	/ earliest date (P1319) year 741	Swanachild (Q291747) date of death (P570)
before 140s	/ latest date (P1326) 140s	Pius I (Q83198) date of birth (P569)
between 586 and 569 BCE	/ earliest date (P1319) 586 BCE / latest date (P1326) 569 BCE	Pythagoras (Q10261) date of birth (P569)
between circa 1600 and circa 1615	/ earliest date (P1319) 1600. / latest date (P1326) 1615. / sourcing circumstances (P1480) circa (Q5727902)	Pieter Mulier the Elder (Q217640) date of birth (P569)
from 1384	/ start time (P580) 1384.	Mikołaj of Ściborz (Q11780990) floruit (P1317)
until 1515	/ end time (P582) 1515.
from 1405 until 1420	/ start time (P580) 1405. / end time (P582) 1420.	Master of Egerton (Q29609) floruit (P1317)
beginning of 11. century	11. century / refine date (P4241) beginning of (Q40719727)	Paraskeva of the Balkans (Q6967370) date of birth (P569)
middle of 18. century	18. century / refine date (P4241) middle of (Q40719748)	Zlata of Meglen (Q2512266) date of birth (P569)
end of April 2011	April 2011 / refine date (P4241) end of (Q40719766)	Hoegaarden 0,0 (Q2198961) inception (P571)
first half of 1900s	1900s / refine date (P4241) first half (Q40719687)	Monogrammist E. D. (Q40912154) floruit (P1317)
summer of 1693	1693. / refine date (P4241) summer (northern hemisphere) (Q40720564)	Hieronymus Janssens (Q3135313) date of death (P570)
autumn of 1653	1653. / refine date (P4241) autumn (northern hemisphere) (Q40720568)	Adriaen van Utrecht (Q367970) date of death (P570)

Caution: distinction between a digital file, and a creative work shown/depicted in a file

When a file on Wikimedia Commons shows/depicts a creative work, date information about the file and about the depicted work are usually very different.

In some cases (when? criteria?) it is best to describe the creative work as an item on Wikidata to keep this distinction clear.

(example)

Modeling various dates and times related to Wikimedia Commons files

Type of metadata	Notes	Wikidata property	Status
Creation date	In case of a photograph: the date the photo was taken In case of a painting or other artwork: the date the painting was completed etc.	inception (P571)	Done
Publication date	First time shared with a wider audience (affects copyright status)	publication date (P577)	Work in progress
Date depicted	Map or other representation of a specific date	date depicted (P2913)
Example	Example	Example	Work in progress

General notes and remarks

• Date properties should be direct, in order to be able to add qualifiers
  • earliest date (P1319), latest date (P1326), refine date (P4241)

Examples

(list files below that provide best practices on how to model various situations)

• 
  Example.jpg Example 1 of good data modelling of situation a
• 
  Example.jpg Example 2 of good data modelling of situation b