The Combining Diacritical Marks block spans U+0300–U+036F, 112 codepoints in Plane 0 (Basic Multilingual Plane). Every one of them is assigned in Unicode 16.0.
All of its characters belong to the Inherited script.
By general category: 112 non-spacing marks (Mn).
The first 72 arrived in Unicode 1.1 (1993); later additions came in 3.0 (10), 3.2 (14), 4.0 (11), 4.1 (5).
Most characters here are combining marks. See combining diacritical marks.