År er et heltal mellem 1583 og 9957 eller mellem 0 og 99 (Der så, som standard, bliver fortolket som år i perioden 1930-2029).
LibreOffice baserer dato og tid på den internationale standard ISO8601.
Kalenderen er baseret på den Gregorianske kalender, der blev indført af Pave Gregor XIII, d. 4. okt. 1582 (Juliansk kalender) som blev sat lige med 15. oktober 1582 i den Gregorianske kalender. Altså første hele år efter den Gregorianske kalender er 1583.
Indført i Danmark 1700. Hvor 18. februar (Juliansk) blev 1. marts 1700 i Gregoriansk kalender
I følge https://en.wikipedia.org/wiki/ISO_8601 :

The standard uses the Gregorian calendar, which serves as an international standard for civil use.[8]

ISO 8601 fixes a reference calendar date to the Gregorian calendar of 20 May 1875 as the date the Convention du Mètre (Metre Convention) was signed in Paris. However, ISO calendar dates before the Convention are still compatible with the Gregorian calendar all the way back to the official introduction of the Gregorian calendar on 1582-10-15. Earlier dates, in the proleptic Gregorian calendar, may be used by mutual agreement of the partners exchanging information. The standard states that every date must be consecutive, so usage of the Julian calendar would be contrary to the standard (because at the switchover date, the dates would not be consecutive).

When you type a formula, after having entered the coordinates (using keyboard or mouse), press ⇧ Shift+F4.

Each press on this combination toggles the presence or absence of the '$' for the row, the column and, where appropriate, the sheet.

Cells can be hidden via the Cell protection tab but this protects the sheet as well. Sometimes, we want to hide some cells without protecting the sheet. That might be the case when we apply conditional formatting Icon set for example, in which values ​​are represented by icons. In this case, it could be useful to hide the values and only show the icons.