What 𞁖 means
It marks transcription, not ordinary Cyrillic spelling.
In some phonological transcriptions, a Cyrillic subscript marks an archiphoneme: a category used where sound contrasts disappear in a particular position. A superscript can mark pronunciation detail instead. The glyph has no fixed sound value; read the transcription key.
The notation predates Unicode. A 1905 example contrasts raised and lowered letters for stronger and weaker vowel values. Published transcription examples of 𞁖 appear in 1973 and 1981.
Don't confuse it with
1Questions people ask
1Why does 𞁖 show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type 𞁖
𞁖\1E056Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.