Alas! I also find that many poses are designed with no translations or rotations applied to the figures' Body (root actor) and everything assigned to the hip (or pelvis). In many instances, a rotation of the middle axis (second of the three axes in the rotation order hierarchy) at or close to 90 degrees leaves that actor in or near gimbal lock (where large rotations of both the other axes are required to effect small adjustments of the "lost" axis - one degree of freedom has been sacrificed). I propose that a "better" solution (IMHO) is to always apply the majority of X and Z translations, and Y rotations to the root actor, leaving Y translations, and X & Z rotations for the hip (or pelvis) actor alone (with only sub-degree or small adjustment translations left for the other hip axes). That eliminates any possibility of gimbal lock, as the hip rotations have no effect on the Body axes. I note that there can be other circumstances where the user needs the figure to perform some in-place rotation about the Y-axis of the hip, and my suggestion there (assuming the figure does not already have separate hip and pelvis actors [dummy actors that distribute their applied rotations to adjacent physical actor do not count here] is to parent the entire figure to a grouping object, and use that to set the Y-axis of the root actor at the desired attitude. I suspect that the original Poser Devs have thoroughly explored all of these scenarios, given the plethora of figure conforming options in evidence: Origins and EndPoints, for example. None of this is any particular help to me in the course of attempting to develop intelligent algorithms for pose matching of disparate figures, except that it probably indicates that I need to abandon the concept of trying to calculate pose adjustment parameters, and instead derive the original figure's actor origins and endpoints (plus an orthogonal vector for orientation [perhaps a quaternion is appropriate here?]) and use those solely for pose matching of the target figure. [Much binding in the marsh to ensue...]