In Italian dates, only the first day of the month may be written as 1º or 1°, and it's more common than just 1.
But it doesn't work in sortable tables. In example below, on it.wiki, all days are sorted correctly except 1.
The sorting code should simply discard those symbols when reading Italian dates.
{| class=sortable
! data-sort-type=date | Date
|-
| 2 maggio 1999
|-
| 3 maggio 1999
|-
| 1º maggio 1999
|-
| 4 maggio 1999
|-
| 5 maggio 1999
|}Other languages may have similar problems, for example I think en.wiki can't sort dates with "1st" etc.