The distal ends of respective segments 330 of each horizontal fan radial 320-N and each horizontal perimeter radial 302, 304 (with respect to the threat system TS) define a unique locality 332-E where E is an integer identifying a respective segment 330 of a specific horizontal fan radial 320-N (or a specific horizontal perimeter radial 302, 304) in relation to the threat system TS. That is, for a