Drawing annotations — what is a leader line? Identify the line type that is a thin solid line starting with an arrowhead or dot and pointing to a note, symbol, or specific feature on the drawing.

Introduction / Context:
Notes and symbols on drawings must be unambiguously associated with the correct features. Leader lines provide that association without cluttering the geometry. Recognizing a leader helps drafters place annotations cleanly and inspectors find the intended callouts quickly.

Given Data / Assumptions:

• Leader lines are thin, solid lines.
• They start with an arrowhead or dot at the feature and terminate at a note or symbol.
• Standards recommend using short, direct leaders that avoid crossing other annotations where practical.

Concept / Approach:
Different line types carry different meanings: dimension lines show measurable spans, extension lines project from features, centerlines locate axes, and leaders connect text to features. Because the description matches a thin line with an arrowhead or dot pointing to a note, the correct term is “leader.”

Step-by-Step Solution:

Verification / Alternative check:
ASME Y14 dimensioning and tolerancing standards explicitly define leader usage and arrowhead styles for note callouts, surface finish symbols, and welding symbols.

Why Other Options Are Wrong:

• Dimension line: carries dimension values with arrowheads at both ends.
• Extension line: extends from geometry to the dimension line but does not point to notes.
• Specification: not a line type.
• Section line: hatching within cut areas of a section view, not an annotation pointer.

Common Pitfalls:

• Leaders that are excessively long or cross other text reduce readability; keep them short and at shallow angles.

Final Answer:
Leader