Motion study-specific mates are mates you create for a motion study that are independent of  the assembly model mates. Using motion study-specific mates, you can create multiple motion studies to analyze model motion with different mates without changing the model. 
To create motion study-specific mates:
- Select a motion study.
- Add mates to the assembly from the motion study.
Motion study-specific mates are listed only on the 
MotionManager design tree. The string 
Local prefaces the name of motion study-specific mates.   
To see that the motion study-specific mates are not part of the assembly model, view the assembly mates from the Model tab.