Exclusions set the edge of your scope. Without them, the general contractor can assume you cover everything in your spec section and everything near it.
Example: a gym equipment proposal excludes electrical wiring and structural steel above the equipment. It also excludes floor sleeves installed by the flooring contractor.
Write each exclusion in plain words and point to the document behind it, such as a by others note. Do not hide behind a long standard list. Exclude what this job gives you reason to exclude. An item required by your spec section may still be yours unless the general contractor accepts the exclusion.