Returns the thickness of the trace entity (DXF 39) in drawing units. Thickness is the extrusion length along the normal. A positive value defines the thickness to be drawn along the normal direction. A negative value defines the thickness to be drawn in the opposite direction from the normal. A zero value defines a trace without thickness.

Example of Working with the Trace Object 

Specific Trace Properties 

OdDbTrace::setThickness() method

OdDbTrace Methods