As discussed in ATR-26508 , NSW-BW coincidences were always enabled, regardless of the presence of NSW in the run. Now, in case of BS input data, the detector mask is retrieved from the dedicated metadata container, checking if NSW detectors (both sides) were taken out from the run.
Default assumption is that both NSWs are included. If sTGC or MM detectors are excluded, then coincidences are not evaluated for that entire side