"Rick Rothstein \(MVP - VB\)"
wrote...
Try this variation on my formula and see if it works (I **think** the "aaaa"
returns the day name with the localized spelling for the computer it is
being run on)...

=IF(DATE($B$5,$B$4,$B9)<=DATE($B$5,$B$4+1,0),TEXT (WEEKDAY(DATE($B$5,$B$4,$B9)),"aaaa"),"n/a")
....

May work for English and German (and other) regional settings, but I
wonder whether it'd fail for French and presumably other romance
language regional setting where 'a' stands for year.

Internationalization is a PITA.