I am researching a U.S. tariff classification issue and, thus, my inquiry is primarily a matter of legal interpretation; however, the law turns on what articles answer to the description "structures and parts of structures" (of iron or steel). The tariff heading (7308) references "structures and parts of structures" and gives a "balustrade" as a specific example.
My research indicates that balustrades can be thought of as structures, in their own right (e.g., a barrier or a boundary foot traffic), or as parts of higher-order structures (i.e., railings in buildings, bridges, roadways, houses, etc.). The articles being classified are the balusters and newells (i.e., the vertical post members of a rail and post balustrade). The balusters are forged iron and steel, decorative, and intended for residential and light commercial use (e.g., stair rails, balcony rails, etc.).
Can anyone assist with engineering or architectural definitions or discussions re "structure," "balustrade," or "baluster" that would help me show that "balusters" are parts of structures and properly classifiable as such? The definitions I'm coming up with are supportive but not very detailed. The tariff provision is as broad and vague as the definition of what constitutes a "structure." That is, the provision would appear to provide for everything from hi-rise structurals to light duty, residential structural items. Any help will be greatly appreciated.