Source rotation using GPS

Dear experts,
As per manual source rotation can be done using /gps/pos/rot1 and /gps/pos/rot2 command in macros . But what these two vectors represents as there is very less explanation in the manual[Geant4 General Particle Source — Book For Application Developers 11.0 documentation].
For example if I have to rotate a planer source +20 degree in z axis with respect to geometry axis. How to calculate these vectors.

Thanks
ROHIT

Hi @rbyadav ,
/gps/pos/rot1 defines the first vector R1 (new x’ axis), [default (1,0,0)]. /gps/pos/rot2 defines the second vector R2(new y’ axis) in the xy plane, [default (0,1,0)].

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Dear repan,
If I am correct then it means that R1 is new rotation x’ axis that makes (cos1, cos2,cos3) angles with original x,y,z axis of geometry and similar to R2??

Thanks
ROHIT

yeah, you are right. the vector R1(presented in the old XYZ reference frame) defines the new x axis .

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