Rests vertical position

A rest's vertical position may be explicitly specified by entering a note with the \rest keyword appended, the rest will be placed at the note's place. This makes manual formatting in polyphonic music easier. Automatic rest collision formatting will leave these rests alone.

\version "2.24"

%% http://lsr.di.unimi.it/LSR/Item?id=159

{
  a'4\rest d'4\rest
}