You can create true sections along a curve. The section planes are set to points on
selected curves. The curve tangent in these points defines the plane normal. The intersection
line between surface and normal plane is the true section in this point.
Before you begin: Open a 3D Shape containing surfaces and curves.
Define your input geometry by doing either of the following:
Select surfaces and click to perform a local analysis.
Click Global/Local to perform a global analysis.
Select Orientation: True.
Select a feature curve and click .
Note:
True sections are not associative. If the original curve is modified, it must be
reselected for the true section calculation.
to perform a local analysis. 
to perform a global analysis. 
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