Note, this algo is not using any away-side ET veto, nor BSMD info. I explored benefits of missing ET (not used before) and got the plot on the right (below) of 2x2 ET  vs. away side ET in the BTOW. The D-region is where Zs should show up.

Fig 2.

Below is example of 1 event of each type - event display courtesy to Matt Walker, the animated version of those events in sketchup is in attachment K.

Fig 3.