What is a possible characteristic for defining classes under regulations?

Defining classes under regulations often relies on attributes or qualities that clearly distinguish one class from another. This approach allows for a more organized system where buildings can be assessed and regulated based on specific measurable characteristics, such as safety features, performance capabilities, or usage types. By focusing on attributes or qualities, regulators can ensure that classifications are applicable and relevant, facilitating proper enforcement of codes and standards derived from these classifications.

While other options like size, cultural significance, and location can influence regulations, they are typically secondary to the inherent attributes of the structures being defined. Attributes provide a concrete basis for categorization, making them particularly useful for regulatory contexts. This is why focusing on an attribute or quality is the most effective method for defining classes under regulations.