offset command on ellipse ...

created an ellipse and then used offset command on it.
No result.
6.8.0 windows test harness:

> ellipse e 0 0 0 100 50
> top
> offset o e 10

Offset curve is not created.

PG's picture

checked help on offset command
Draw[44]> help offset
offset : offset name basename distance [dx dy dz]

If the optional parameters dx dy dz are set , then ellipse is created.
Draw[49]> offset o e 10 0 0 1

Is it requird every time to give these vector direction ?