How to know if the sphere is correct tracking

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For filtering purpose, I would like to know if the sphere tracking is correct 
or not. 
I saw in the api and by testing that the value in PSMoveState called 
tracking_flags appears to be the good candidate because when I am correctly 
tracked the value is 3 and 0 when not tracked at all. 
Can you tell me first if I am right and in that case what is the meaning of 1 
and 2 values ? 
Regards,
Julien

Original issue reported on code.google.com by briss...@gmail.com on 6 Jan 2012 at 3:37