A machine with a clearly defined function described by a specific heading in the chapter is classified there, even if it performs ancillary operations. Heading 8479 is a residual provision for machines that have an individual function not covered elsewhere in Chapter 84; it should only be used after confirming no more specific heading applies.

Heading 8486 specifically covers machines and apparatus used in the manufacture of semiconductor boules, wafers, devices, or integrated circuits, as defined by Chapter 84 Note 11(C). General machine tools in the 8456–8465 range are for broader metalworking or material-removal operations and are not limited to semiconductor fabrication.

Parts that are identifiable as suitable for use solely or principally with a specific machine are generally classified with that machine's heading or in the dedicated parts headings (such as 8409 for engine parts or 8431 for lifting-equipment parts). However, parts that are more specifically described by another chapter—such as electrical components—follow their own chapter's rules.