Which type of line points directly to a surface for the purpose of dimensioning or adding a note?

A leader line is specifically designed to point directly to a feature on a drawing in order to dimension it or add annotations. This type of line creates a clear connection between the textual information and the part or dimension it refers to, which aids in clarity and understanding in engineering and technical drawings.

Leader lines typically have an arrowhead at one end, indicating the exact point of interest, and they allow for more flexible positioning than dimension lines or extension lines. This makes them particularly useful for pointing to surfaces with notes or specific dimensions that are necessary for fabrication or assembly.

Other types of lines, such as dimension lines and extension lines, serve different purposes. Dimension lines indicate the measurement of a specific feature, while extension lines extend from the object being measured to the dimension line. Center lines, on the other hand, are used to indicate the centers of circles or symmetrical objects. Each type of line has a distinct role in technical drawings, but the leader line is the only one specifically focused on directing attention to a particular surface for annotation or dimensioning.