extrusion direction

[Snipe]

I am writing a program that reads a dxf-file and draws it in .NET.
But now I have a problem with "extrusion direction". I can't seem to find how this should influence the calculations of the points to draw.

Now I don't look at the extrusion direction. But now I have a file where there are arcs witch have 0,0,-1 as extrusion direction. This causes these arcs to be drawn in the wrong place.

Can anybody explain how you should use the extrusion direction when calculating the points of the arc?

[Snipe]

Nobody who knowes anything about this????? :unsure:

[CarlB]

Following sites may be helpful:

http://www.autodesk.com/techpubs/autocad/acadr14/dxf/object_coordinate_systems_40ocs41_al_u05_c.htm

http://astronomy.swin.edu.au/~pbourke/dataformats/dxf/dxf10.html