[casper] Question about the use of aux_sync_out interface(J11)

[peter]

hi all,
      Can someone tell me what is the use of the aux_sync_out ?This is the 
aux_sync_out cable from J11 on the Roach2.The J10 is for the aux_sync_in,all 
this from the all roach2s can be put into a sync singal like 1pps.But what is 
the J11 use for?
Best regards!
peter