Canberra strike - System 9

[redsetter]

I was browsing through a Canberra strike squadron ORB the other day - looking at the period circa 1966, covering the changeover from LABS to laydown. There's a few mentions of "System 9" bombing sorties. Wondered whether any old Canberra strike hands could expand on what that was. Is this a reference to Decca - or something else entirely ?

thanks,

RS