The Symbols for Legacy Computing Supplement block spans U+1CC00–U+1CEBF, 704 codepoints in Plane 1 (Supplementary Multilingual Plane). 686 are assigned in Unicode 16.0; the other 18 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: 676 other symbols (So), 10 decimal digits (Nd).
The first 686 arrived in Unicode 16.0 (2024).
Because it lies outside the BMP, every character here takes four bytes in UTF-8 and a surrogate pair in UTF-16.