Well, almost nothing (I kid – mostly).
John Ericson, Horn Professor at Arizona State University, and one of the founders of the French horn website HornMatters.com, has a book about playing the <em>A Mello Catechism: A Guide to the World of Mellophones and Marching Horns</em></span>.
This book discusses the history, technique, and equipment used in marching bands and drum corps, and is a useful resource if you're wanting more information about that world.
John posted an excerpt from that book over on <a href="http://hornmatters.com/2018/03/book-excerpt-playing-more-musically/" target="_blank" rel="noopener">HornMatters.com, in which he provides an answer to the eternal question: “How can I play more musically?”
You can’t play musically without total technical control over every aspect of dynamic and articulation. You may have wonderful musical concepts, but you won’t be able to communicate them to listeners unless you have the full vocabulary of dynamics and articulations mastered! The process for mastering this vocabulary is practice. It won’t happen magically; you have to learn this skill well and be guided by competent teachers and mentors.
Beyond that basic issue, there are two ways to approach preparation of musical works for performance, and both of these are correct. Depending on the work I will chose to lean more toward one or the other.