When specifying dimensions, which characteristic is true for diameter indications?

When specifying dimensions, particularly diameters, the characteristic that is true is that they should be marked with specific symbols. This is crucial because using symbols ensures clarity and precision in engineering drawings. The diameter symbol (often represented as a circular symbol before the dimension) effectively communicates that the dimension being referenced is for a circular feature, thus helping to avoid misunderstandings.

In this context, while other characteristics may apply to certain situations, the use of specific symbols is essential in standardized engineering practices. It allows for universal comprehension of the drawing across different disciplines and professionals. Proper notation simplifies communication, particularly in complex designs where multiple dimensions and features are present. Therefore, marking diameter indications with specific symbols is a fundamental aspect of effective engineering communication.