Catalan Zodiac Rose S.XV

[oshfdk]

The circle is letter 'o' and marks the number as an ordinal. In Italian:

VIIII= nove (nine)

VIIII°= Nono (ninth)

Thanks! But I still think it's more likely this particular o in the image above is used to mark four of the same characters in a row. Marking just a random subset of numbers as ordinals and only those that have I or X repeat 4 times would be too much of a coincidence. As far as I can see, in that table this o appears over all instances of IIII or XXXX and nowhere else.

Edit: one exception though: CXXXX has no o, unless this is not a C, but some kind of modifier, making this ?XXX