What type of line on a print represents edges of a part that can be seen?

The type of line on a print that represents edges of a part that can be seen is known as object lines. These lines are typically bold and continuous, making them easily identifiable. They outline the visible edges of a component in a technical drawing, allowing anyone interpreting the print to clearly understand the shape and dimensions of the part.

In contrast, guidelines are used to help in the arrangement of the drawing, centerlines indicate symmetry and the centers of circles or arcs, and phantom lines are employed to represent alternative positions or adjacent parts. Each of these has its specific function within a technical drawing, but object lines are specifically responsible for depicting the visible contours of parts.