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The implementation of BSpline differs from previous complex forms.
The BSpline is created constraint to be polynomic (non-rational), with radius of first circle and equality constraints.
Hide unused internal geometry considers as unused the following constraints:
- A pole which has equality constraints with another pole of the same bspline
- Any radius constraint on a pole
Deletion of a BSpline will delete the internal geometry that is unused as per the definition above.
If there is another constraint (other than the Internal alignment constraint) it will leave the internal geometry having such constraint undeleted.
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