Fine line work usually angular giving tone to sectioned surfaces is called what?

The term that accurately describes fine line work that is typically angular and provides tonal contrast to sectioned surfaces is "section lining." This technique is specifically used in architectural and engineering drawings to indicate different materials, textures, or areas within a section view. Section lining helps convey information about the composition and characteristics of the materials represented within a drawing, making it easier for viewers to interpret the structure or object being depicted.

In technical drawings, section lining is structured to be distinct and systematic, often using specific patterns or styles for different materials, which aids in clarity and standardization across various drawings. This practice enhances visual communication in engineering, architecture, and related fields by providing essential details regarding the materials used in construction or design.

While drafting generally pertains to the overall process of creating detailed technical drawings, and shading refers to a technique used to suggest depth and volume through gradients of tone, cross-hatching is another method involving the use of intersecting lines for shading, but it does not specifically apply to sectioned surfaces in the same context as section lining does. Thus, section lining is the most fitting choice for the description provided in the question.