Hi Peer,

re:
> So, should I include these factories, or will trying to use them in a
> custom javascript command cause problems?

arrow3d - this one can be used by a script.
backgroundimagerotatewheel - this one is internal only and can't be created by a script command
baserectangle - this is a base class for the rectangle and rectcenter factories, it can't be created by itself
calcarea - could be used by a script
calclength - could be used by a script
calcvolume - could be used by a script
drag - could be used by a script
dragpointoncurve - internal only can't be created by a script command
labelpoint - factory name is just "label", could be used by a script
objectframerotate - could be used by a script, maybe
objectframerotatewheel - could be used by a script, maybe
objectframescale - could be used by a script, maybe
pdfencoding - there isn't a factory with this name
scalenonuniform - could be used by a script

But some of these are made for specific circumstances like the object frame and drag ones and it's possible they might not be able to do anything outside of that.

- Michael