The Byzantine Musical Symbols block spans U+1D000–U+1D0FF, 256 codepoints in Plane 1 (Supplementary Multilingual Plane). 246 are assigned in Unicode 16.0; the other 10 are reserved for future characters.
All of its characters have the script value Common: they are shared across writing systems rather than tied to one.
By general category: 246 other symbols (So).
The first 246 arrived in Unicode 3.1 (2001).
Because it lies outside the BMP, every character here takes four bytes in UTF-8 and a surrogate pair in UTF-16.