•C — Case conversion•C Y folds case.
•C 'AbC' ⍝ 'abc'
1•C Y uppercases; ¯1•C Y lowercases.
1•C 'AbC' ⍝ 'ABC'
¯1•C 'AbC' ⍝ 'abc'
Unicode simple mappings preserve shape and nesting; non-character leaves stay unchanged.