DDT Lines

Visible Line

Represents outside of object being drawn

Hidden Line

Edges and outlines of objects not visible

Section Line

Shows material on a cut section

Center line

Indicates Symmetry, center points or axes

Dimension Line

Denotes dimensions

Extension Line

Extends the surface or point away from view for dimensioning

Cutting Plane Line

Shows where imaginary cuts take place

Viewing Plane Line

shows where the view would normally appear

Short Break

Smooth curves, terminates a view to conserve space

Long Break Line

Heartbeat, Allows removal of long central portion of an object

Phantom Line

Shows the alternate position of a object

Chain Line

Used to indicate an area that is to receive special attention

Short Break, Visible lines, Cutting plane, Viewing Plane, Chain

Thick Lines

Center, Long Break, Dimension, Extension, Section, Phantom, Hidden

Thin Lines

Phantom, Hidden, Cutting plane, Viewing Plane, Chain

Dashed lines