The Offset button creates a displacement copy of the selected object a parallel distance away as specified in the Offset Reveal field.
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See: Offset Function in Trace
Enclosed Objects:
Arcs and Curves greater than 180 Degrees use the same rules as closed objects.
Unenclosed Objects:
For unenclosed objects the arrow buttons depend on the direction of travel of the vector segments, starting from the line’s start point.
The Left < button offsets Clockwise and Right > button offsets Counter-Clockwise.
If it doesn’t Offset in the expected direction, click Undo and click the other Offset Direction.