Thanks for the tutorials - very much appreciated. I've quickly read through the quaternion one, and I'm already much happier. Need to read it again a few times.

The matrix tutorial will take a bit longer...

Regarding actor.Orientation() giving the prop's original orientation (as defined in the PP2 I assume?) - that would explain why it's the same in both cases, despite the prop being oriented differently. (The PoserPython Manual description "Get the orientation of the actor’s coordinate system (x,y,z ordered rotation)." is clearly wrong - the prop origin marker (three mutually perpendicular green lines) in my two cases is clearly different)

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The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.