The generic meaning of xlfn is “unsupported function”.
In the example shown, the UNIQUE function is used to extract unique values from a range of data.
UNIQUE is only available inExcel 365, and was introduced in 2020.
When the workbook is opened in an older version of Excel, the __xlfn prefix appears.
Note that the original result is still displayed.
However, the formula will not update to show a new result if data changes.
