Which requirement must a reusable container meet to be considered usable?

A reusable container must be capable of protecting unserviceable items against further deterioration to be considered usable. This requirement is crucial because the primary function of any container, especially one that is used for storage or transport, is to safeguard the contents it holds. For unserviceable items, which may be susceptible to environmental factors such as moisture, dust, or physical damage, the container must provide adequate protection to prevent further deterioration.

If a container does not effectively protect its contents, it could lead to increased damage, loss of functionality, or even safety hazards. This requirement ensures that items retain their integrity until they can be properly disposed of or restored.

While factors like transportability, color-coding for inventory, and material recyclability are important in certain contexts, they do not directly impact the primary function of protecting items, making them secondary when considering the usability of a reusable container.