Chapter 90 covers optical, photographic, measuring, checking and medical instruments and apparatus. Its logic is neither material nor technology but function: to observe, measure, check, treat.
That is why it often wins against Chapter 85. A wholly electronic device that measures a quantity belongs here, not in Section XVI. Parts follow the chapter's own Note 2, which is distinct from the Section XVI rule: a part identifiable as suitable for use solely with an instrument of Chapter 90 stays in Chapter 90.
Every number opens on the lines beneath it, down to the eight-digit statistical code.