CHANNEL function qos stats

hi

the CHANNEL function give some stats about QoS.

sample
ssrc=1537543648;themssrc=1733303708;lp=0;rxjitter=0.000063;rxcount=3792;txjitter=0.000381;txcount=3804;rlp=0;rtt=0.003000

does anyone know where i can get documentation on how to use this data to create a QoS score.
Thanks