Tariff classification of optical and precision instruments guides schedule placement and customs treatment for related goods. Customs Tariff provisions designate classification headings for optical, photographic, cinematographic, measuring, checking, precision, medical or surgical instruments and apparatus; clocks and watches; musical instruments, and their parts and accessories within the relevant chapters of the First Schedule, grouping these goods to guide tariff treatment, nomenclature and schedule placement as a distinct tariff sector for import and customs administration.