What characteristic defines visually graded dimensional lumber?

Visually graded dimensional lumber is characterized primarily by grading based on appearance. This involves evaluating the wood's surface characteristics, such as the presence of knots, grain patterns, and other visible features that affect its strength and utility. The grading process helps determine the appropriate use of the lumber in construction and other applications, ensuring that only suitable pieces are used for load-bearing or structural purposes.

The other aspects, such as moisture content, surface dry condition, and the manufacturing process, play roles in lumber quality and performance but do not define the visual grading system itself. While moisture content can affect wood strength and durability, it is not a direct factor in visually grading lumber. The surface dry condition is indeed a property of lumber that may impact its final applications but is not related to the grading criteria by appearance. Meanwhile, the manufacturing process refers to how the lumber is cut and treated but does not pertain to the visual grading assessment based on physical characteristics visible to the eye.