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            <b><a class="bz_bug_link 
          bz_status_UNCONFIRMED "
   title="UNCONFIRMED - Calc: calcuate weeknumber-year missing in 2021"
   href="https://bugs.documentfoundation.org/show_bug.cgi?id=139421#c4">Comment # 4</a>
              on <a class="bz_bug_link 
          bz_status_UNCONFIRMED "
   title="UNCONFIRMED - Calc: calcuate weeknumber-year missing in 2021"
   href="https://bugs.documentfoundation.org/show_bug.cgi?id=139421">bug 139421</a>
              from <span class="vcard"><a class="email" href="mailto:mikekaganski@hotmail.com" title="Mike Kaganski <mikekaganski@hotmail.com>"> <span class="fn">Mike Kaganski</span></a>
</span></b>
        <pre>(In reply to Regina Henschel from <a href="show_bug.cgi?id=139421#c3">comment #3</a>)
<span class="quote">> I cannot confirm the initial reported results
> =TEXT(A1;"yyyy-WW") returns correctly the ISO week number
>   2020-53 for date 2020-12-31.</span >

This depends on language selected in Format Cells->Numbers. For e.g. ru-RU or
en-US, this gives 2020-1. For de-DE, it returns 2020-53.

<span class="quote">>   2021-53 for dates 2021-01-01, 2021-01-02, 2021-01-03</span >

This is exactly what OP complains about: the week number 53 should be *of year
2020* for dates in the beginning of year 2021, if use de-DE; or week 1 of *year
2021* is needed for dates in the end of 2020 with en-US.

Note the "[YYYY] indicates the ISO week-numbering year which is slightly
different from the traditional Gregorian calendar year" in [1].

<a href="https://en.wikipedia.org/wiki/ISO_8601#Week_dates">https://en.wikipedia.org/wiki/ISO_8601#Week_dates</a></pre>
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