Final answer:
Section lines or cross-hatching are used in a section view to show where the material is cut, revealing interior surfaces behind the cutting plane in technical drawings.
Step-by-step explanation:
The lines used in a section view to show where the material is cut are known as section lines or cross-hatching. These lines are employed to represent the surfaces that would be visible behind the cutting plane. In technical drawing, it is essential to convey the interior details of a part or assembly that are not visible from the outside.
Section lines help in communicating how a component is composed internally and can also provide information about the type of material used through various standardized patterns. The use of contour lines in the section view also helps define the extent of the cut surfaces and enhances the readability of complex components. They are distinct from other line types such as outline, which delineates object boundaries, and orthogonal, which are used in perspective drawings.