What is the purpose of a leader line on a drawing?

• A. To indicate hidden features
• B. To attach a note or dimension to a specific feature
• C. To show the overall scale
• D. To identify the author

Answer: (B)

Leader lines are used to attach a note or a dimension to a specific feature on a drawing. They extend from the feature to the text so readers know exactly which part the note or measurement refers to, keeping the drawing uncluttered and unambiguous. This is how you communicate details like size, finish, or special instructions directly tied to a particular edge, hole, or surface.

They are not about showing hidden features—that’s conveyed by hidden lines. They don’t indicate the overall scale, which is set by the drawing’s scale and general dimensioning conventions. And they aren’t used to identify the author, which is done in the title block. For example, a leader line might point from a hole to a note that says “Ø10 mm, tolerance ±0.1 mm,” ensuring anyone reading the drawing knows exactly which feature the note describes.