Thin but dark, dashed line that indicates the edge of a feature that is hidden in a particular view.
hidden line
The thin but dark, dashed line that indicates the edge of a feature that is hidden in a particular view is called a hidden line. It is used to represent a feature that exists on an object but cannot be seen in a particular view because it is behind another object or is obscured by another feature. Hidden lines help to clarify the shape and dimensions of an object in technical drawings, making it easier to understand and manufacture. Hidden lines are usually drawn using a dashed pattern, typically with short dashes and long spaces. In some cases, hidden lines may also be drawn using a solid line that is thinner than the visible lines used to represent features that can be seen in the view.
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