I found with Poser 3 that if a curve segment X is child of a non-curve segment Y, the front end of X is distorted to make it point at the geometrical center of Y. Thus, I found that if the root segment of a model is curve, in the posed or exported form its front end is distorted to make it point at the geometrical center of the whole model, since the root segment's parent is the model's BODY. The remedy is to interpose between X and Y a very short non-curve non-rigid segment.