Drawing a guide line in a 3D modeö

Hello,
I just started to program with OpenCascade and it's quite impressive to see the functionality. I want to program an application to generate NC programs based on some special geometry. To represent the orientation of the tool in the NC program I want to draw lines for every program coordinates. This means I need only a straight line between 2 points. But according to my information I found only these geometrical elements in the documentation which seems to be suited:
- Line --> Is okay but is an endless representation and does not end at the defining points
- Edge --> Is the edge of an body and not only a line
- Curve --> Is more complex because the definition includes the possibility of splines and I need only a straight line
Can you please give me some input which element is suited from your point of view? Would really appreciate any support.

Thanks in advance.