What are thin lines that end in an arrow or dot used to indicate?

Thin lines that end in an arrow or dot typically indicate reference dimensions in technical drawings and construction documentation. These lines serve to provide additional information about the dimensions that may not be directly associated with the main features of the drawing but are still important for clarification or understanding the context of the dimensions.

Reference dimensions are often used to give approximate sizes or to show the relationship between different parts of a structure without being tied to a specific required tolerance or measurement. This allows designers, engineers, and builders to see distances or sizes that facilitate comprehension of the overall drawing without altering the definitive dimensions that dictate the actual construction.

Utilizing thin lines with arrows or dots keeps the drawing uncluttered while still providing crucial information that enhances interpretability. This graphically communicates the intent behind the dimensions presented, ensuring that all users of the drawing can follow and understand the design intent thoroughly.