U+1D7B Latin Small Capital Letter I with Stroke

The Wikipedia has the following information about this codepoint:

The close central unrounded vowel, or high central unrounded vowel, is a type of vowel sound used in some languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɨ⟩, namely the lower-case letter i with a horizontal bar. Both the symbol and the sound are commonly referred to as barred i.

Occasionally, this vowel is transcribed ⟨ï⟩ (centralized ⟨i⟩) or ⟨ɯ̈⟩ (centralized ⟨ɯ⟩).

The close central unrounded vowel is the vocalic equivalent of the rare post-palatal approximant [j̈].

Some languages feature the near-close central unrounded vowel (), which is slightly lower. It is most often transcribed in IPA with ⟨ɨ̞⟩ and ⟨ɪ̈⟩, but other transcriptions such as ⟨ɪ̠⟩ and ⟨ɘ̝⟩ are also possible. In many British dictionaries, this vowel has been transcribed ⟨ɪ⟩, which captures its height; in the American tradition it is more often ⟨ɨ⟩, which captures its centrality, or ⟨ᵻ⟩, which captures both. ⟨ᵻ⟩ is also used in a number of other publications, such as Accents of English by John C. Wells. In the third edition of the Oxford English Dictionary, ⟨ᵻ⟩ represents variation between /ɪ/ and /ə/.