The Bopomofo block spans U+3100–U+312F, 48 codepoints in Plane 0 (Basic Multilingual Plane). 43 are assigned in Unicode 16.0; the other 5 are reserved for future characters.
All of its characters belong to the Bopomofo script.
By general category: 43 other letters (Lo).
The first 40 arrived in Unicode 1.1 (1993); later additions came in 5.1 (1), 10.0 (1), 11.0 (1).
43 characters are East Asian Wide or Fullwidth and take two columns in terminals.