Should DB errors 555 and 558 be adapted for julian/gregorian calendar?

+7 votes
88 views
This is inspired by the result of an error report run on King Charles VIII of France (Valois-273)

Many pre-1600 profiles with a Wikidata counterpart trigger errors 555 and/or 558, obviously because one profile uses the Gregorian calendar and the other uses the Julian one, resulting in a (roughly) 10 days difference between the dates.

I understand Wikitree policy is to use Gregorian dates whenever possible. I don't know about Wikidata. Some dates entered into Wikitree may be Julian where they should be Gregorian, but I'm not sure. Right now I tend to tag those errors False when they concern a profile before 1600 (roughly) and the difference is about 10 days, with a comment  like "Julian/Gregorian calendar ambiguity".

Could the error report be adapted to avoid raising false errors, or a more comprehensive explanation added to the help page for these two errors? I'm not sure what the appropriate solution is and of course the issue is complex since countries switched to Gregorian at different periods (beware of Wikidata dates imported from Russian Wikipedia !). Here is a list: https://en.wikipedia.org/wiki/List_of_adoption_dates_of_the_Gregorian_calendar_per_country

Thank you!

(Adding euroaristo and notables tags because of the Wikidata issue).
WikiTree profile: Charles VIII de France
asked 2 days ago in The Tree House by Isabelle Rassinot G2G6 Mach 2 (23,390 points)

3 Answers

+2 votes

I agree 100% a genealogy website that is world wide should better support dates and different calendars

We need

  • precision = how exact a date is e.g. day, month, year decade
  • define a range
    • before, after....
  • calendar used

I suggested in aug 2016 a quick and dirty solution that we should use a template to tell what calender is used ==> 

  1. The Project database error report will understand it and can compare with Wikidata/Wikipedia  ==> No errors
  2. A reader understand what calendar this date used ==> No guessing for the WikiTree reader 

See a draft of the template I created that has never been used Template:Calendar

answered 2 days ago by Magnus Sälgö G2G6 Pilot (184,460 points)
edited 1 day ago by Magnus Sälgö

In Wikidata Charles VIII de France is wd:Q134452 ==>

  1. Query
  2. Result
    1. That shows
      1. Timeprecision
        1. A date can be defined to be exact, month, year, decade....
      2. Timezone used
      3. Timecalendar e.g. Proleptic Julian calendar

By changing the Q number you get the result for another person e.g. Medici-19 is Q48544 ==>

  1. query
  2. result

A more technical approach is check the data structure how its stored in WIkidata and can be accessed....

  1. Charles VII de Frances Q134452
    1. P569 is birth
    2. P570 is death
       "P570": [
                          {
                              "mainsnak": {                            "snaktype": "value",                           "property": "P570",
      "datavalue": {
      "value": {
      "time": "+1464-08-01T00:00:00Z",
      "timezone": 0,
      "before": 0,
      "after": 0,
      "precision": 11,
      "calendarmodel": "http://www.wikidata.org/entity/Q1985786"                                },
      "type": "time"},
      "datatype": "time"
                              },
  2. Medici Q48544 

See also earlier discussion G2G

Well. Wikidata has 9 July for Charles VIII and Wikitree has 30 June. The difference is the same for his DOD.

But, if Wikitree used the Gregorian calendara and Wikidata the Julian one, it should be the other way around (i.e. the Julian calendar is roughly 10 days behind the Gregorian one - for this period). Correct?

I'm confused. One thing is certain; the pre-requisite for this to work is to know which calendar your source is using.

>> One thing is certain; the pre-requisite for this to work is to know which calendar your source is using.

And Wikitree should make it easy for the reader and show what calender we use.... today its some unspoken rules... that at least Project Database error and I has problem to understand ;-)

Good presentation I found a link to in G2G

Maybe to work out Charles VIII dates, we need to check sources closer to the time he lived?

Anselme, 3rd edition has 30 June 1470, but we don't know whether that date has been altered to match a different calendar?

I don't think Père Anselme says which calendar he is using, but it's very unlikely he would have converted pre-1582 dates to a proleptic Gregorian calendar though.

There is some evidence: we know for certain that his dates match those recorded by Louise de Savoie for the births of her grandchildren. Louise was recording contemporary events and could not have used another calendar than Julian. (Louise's diary, quoted in Medieval Lands, vs. Anselme's works accessed through Gallica).

I'll come back to this issue after the Clean-a-thon (my team turns out highly competitive, can't let them down !)

Wikidata can be a good candidate to start finding sources and get an understanding of calendar used. I have no skills in this type of genealogy.

see 

+3 votes
In France you also have the Republic Calendar https://en.wikipedia.org/wiki/French_Republican_Calendar
answered 2 days ago by Laura Bozzay G2G6 Mach 6 (62,930 points)

Oh yes. One thing with the Republican/Revolutionary Calendar is that dates in this format won't be accepted by Wikitree. And there's no ambiguity. On the other hand, several profiles from gedcom downloads have missing dates because the revolutionary format dates were not accepted.

When entering a date from that era (in France, 1793-1806, but the calendar was also used in other parts of Napoléon's empire, like current Belgium and Netherlands, Luxemburg...) I always write out both forms (revolutionary and gregorian) in the biography.

Here is the converter I use (there are lots of others).

0 votes

Another complex profile

  1. WikiTree Распутин-1
    1. Born 21 Jan 1869
    2. Died 30 Dec 1916
  2. Wikipedia Grigori_Rasputin
    1. Born
      1. Old style 9 January 1869
      2. 21 January 1869
    2. Died
      1. Old style 16 dec 1916
      2. 30 december 1916
  3. FindAgrave #7304586
    1. Born Jan. 10, 1872
    2. Died  c. Dec. 30, 1916
  4. Wikidata Q43989
    1. Born 9 januari 1869Juliansk
    2. Died 17 december 1916Juliansk  

NOTA BENE:  Easy solution in Wikipedia to explain the different calenders used. What is needed

  1. Create a space page to explain Old style
  2. Add both dates in the Bio section with the link to the Old style page
  3. Negative
    1. Can be a problem for Project Database Error to understand but that could be addressed with a template
answered 2 days ago by Magnus Sälgö G2G6 Pilot (184,460 points)
edited 1 day ago by Magnus Sälgö

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