relativistic factor, 	HIGHLY restrictive conditions!!! 
	- RFp = RFo, particle is at origin (both reference frames)
	- t=0  
	- Rocs(POIo) = Rpcs(POIo(t),t=0)   (careful! ...)
	- This does NOT apply to :
		- a particle moving towards the origin of [RFo, RFp] (only motion away from origin)
		- motions perpendicular to path of particle
		- rotations
	- ?nyet???  or a POIo moving in the direction of flight of the particle, so 
		- cos(Aθpc(POIo(t),t)) = 1  
		- sin(Aθpc(POIo(t),t)) = 0  
	As K1(t=0) = 0, and ∂[∂(t): K1(Aθpc(POIo(t),t=0) = 0) then no K1-related terms are passed on, it can be ignored
	in [steps, iterations] subsequent to (4-33).
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