U+1D10 Latin Letter Small Capital Open O

The Wikipedia has the following information about this codepoint:

Finno-Ugric transcription (FUT) or the Uralic Phonetic Alphabet (UPA) is a phonetic transcription or notational system used predominantly for the transcription and reconstruction of Uralic languages. It was first published in 1901 by Eemil Nestor Setälä, a Finnish linguist; it was somewhat modified in the 1970s.

FUT differs from the International Phonetic Alphabet (IPA) notation in several ways, notably in exploiting italics or boldface rather than using brackets to delimit text, in the use of small capitals for voicelessness, and in more frequent use of diacritics to differentiate places of articulation.

The basic FUT characters are based on the Finnish alphabet where possible, with extensions taken from Cyrillic and Greek orthographies. Small-capital letters and some novel diacritics are also used.

Unlike the IPA, which is usually transcribed in Roman typeface, FUT is transcribed in italic and bold typeface. Its extended characters are found in the Phonetic Extensions and Phonetic Extensions Supplement blocks. Computer font support is available through any good phonetics font, though lower-case and small-capital may not be visibly distinct in letters such as o where these look similar.