<li>If the path of extrusion is curvilinear, at each iteration the
extruded elements are rotated to keep its initial angularity to the
curve. By default, the <b>Base Point</b> around which the elements
- are rotated is the mass center of the elements, however, you can
- specify any point as the <b>Base Point</b> and the elements will be
- rotated with respect to this point.<br>
+ are rotated is the mass center of the elements (note that it can
+ differ from the gravity center computed by \a Geometry module for the
+ underlying shape), however, you can specify any point as the <b>Base
+ Point</b> and the elements will be rotated with respect to this
+ point.<br>
Note that only the displacement of the <b>Base Point</b> exactly
equals to the path, and all other extruded elements simply keep
their position relatively to the <b>Base Point</b> at each
