What is true about the symbol for cast iron in technical drawings?

In technical drawings, the symbol for cast iron is indeed utilized for section lines. Section lines are used to indicate where a cut has been made through a material, enabling viewers to understand the internal features of a part. The specific pattern or representation for cast iron is distinct and helps convey important information about the material properties and the desired section view. This specific representation aids in identifying cast iron components at a glance on welding prints and engineering drawings, which is crucial for interpreting design intent and material specifications.

The other options do not accurately reflect the role of the symbol for cast iron. While it may have unique characteristics, its purpose in section lines highlights its importance in technical drawings rather than suggesting that it is exclusive to cast iron or equivalent to all metals. Therefore, its role in section representation is critical for clarity and communication in welding and fabrication practices.