What kind of line is used to represent the placement of a dimension?

The line used to represent the placement of a dimension is referred to as an extension line. Extension lines extend from the edges of the object being measured and are crucial for indicating where dimensions start and end. These lines are drawn perpendicular to the dimension line and provide a visual reference to ensure the dimension is clearly associated with the part of the object being measured.

Using extension lines allows for clarity in the drawing, helping fabricators and welders to accurately interpret dimensions without ambiguity. This is essential in welding print reading, as precision is key to ensuring proper assembly and alignment of parts. Dimension lines, which are indeed important in conveyance of measurements, are supported by the extension lines that indicate their specific beginning and endpoints.

In contrast, hidden lines are used to show features that are not directly visible from the current view, and center lines indicate the center axis of circular features or components. Therefore, the role of extension lines is unique and essential for proper dimension representation.