I am a new LilyPond user. So far I have been quite pleased with the program. I was trying to find box notation in the documentation, but failed to do so. What I need is an unfilled box that will surround some portion of music, and also a horizontal line extending from the right side of the box. This is used for aleatoric music. Here's an example of what I'm looking for:
https://www.rpmseattle.com/of_note/wp-content/uploads/2012/02/120205_boxed_notation_final1.png (Note that there is a small vertical line at the end of the horizontal line. I don't want that, but others might.)
