The Spacing Modifier Letters block spans U+02B0–U+02FF, 80 codepoints in Plane 0 (Basic Multilingual Plane). Every one of them is assigned in Unicode 16.0.
By script: Common (64), Latin (14), Bopomofo (2).
By general category: 43 modifier symbols (Sk), 37 modifier letters (Lm).
The first 57 arrived in Unicode 1.1 (1993); later additions came in 3.0 (6), 4.0 (17).
20 characters here have compatibility decompositions: they are formatting variants of other characters and are replaced by them under NFKC and NFKD. See normalization.