What is the primary use of a dimension line on a blueprint?

• A. It shows the size of a feature with extension lines
• B. To indicate the orientation of the drawing
• C. To indicate the publication date
• D. To specify the scale of the drawing

Answer: (A)

Dimension lines communicate the size of features on a blueprint by showing the distance between extension lines that touch the edges of the feature. They’re drawn outside the object with arrowheads at the ends and a numeric value placed near the line, and extension lines connect the feature to the dimension line so you know exactly which measurement is being specified. This setup lets fabricators or builders know the precise size to cut or form. Orientation, dates, and overall drawing scale are indicated by other conventions on the plan (like a north arrow or title block notes), not by the dimension line itself. So the primary use is to indicate the size of a feature.