Range suggestions abound online, divided by skill level, resonance, and so on. Range is also a big part of trumpet culture: how do trumpet players flex on each other? "I can play higher than you."
However, I've only seen one chart specifically for composers, giving prudent range limits for starting a line. For example, a trumpet part whose first note is C6 is at best a very advanced part, and more likely just a badly-written one. The thing is, I don't remember what this chart said, and can't find it.
Are there reliable suggestions for how high (or low) a brass part can start on, without approaching the note from below? How much does this depend on skill level?