RelConnectsRigidLink: Help

[jorgebslu]

Hi, I am quite new on SAF format.
I am importing RelConnectsRigidLink and it is not clear for me how the Local Coordinate System is determined.

Could anyone provide some help on how the LCS is determined ?
The sentence: "Local coordination system is given by master node and its parent object." is not clear at all for me.

Thanks in advance.