[jeffbee]

Oh, I read that as an independent statement, rather than one qualifying the first.

[jordanwallwork]

You read "where the main mode of pitch control is by moving the tuning slide" as an independent statement? What does that mean on its own?

[jeffbee]

The interrupting parenthetical was so disruptive to the sentence that I thought it said, essentially, "The trombone is the only brass instrument. Parenthetical. The trombone is played by moving the slide."