Putting parentheses around non-note objects
Various objects may be parenthesized as well as notes: in this example, the articulation mark is printed between parentheses.
\version "2.24.0"
%% http://lsr.di.unimi.it/LSR/Item?id=421
\relative c' {
< c d g >2-\parenthesize -.
\once \override Parentheses.font-size = #0
c-\parenthesize \trill
}