What type of line is typically used to indicate the center of a hole or circle in technical drawings?

In technical drawings, the center line is specifically used to indicate the center of a hole or circle. This type of line is characterized by its alternating long and short dashes, which help to distinguish it from other types of lines. The primary function of a center line is to represent symmetry and the center point of circular features, making it a crucial element in accurately communicating the design intentions to engineers and manufacturers. By showing the center, it allows for proper alignment and placement of other components around the hole or circle.

The other line types serve different purposes; phantom lines are used to indicate elements that are not currently part of the object being detailed but are relevant for understanding, while hidden lines represent edges that are not visible from a certain viewpoint. Dimension lines provide measurements of features, but they do not indicate centers. Thus, the center line is the only line type specifically dedicated to indicating the center of circular features in engineering drawings.