This applies the same CLP-1-first selective discard logic as cardClp0CbrThreshold, but to the real-time VBR queue instead of CBR. This applies the same selective CLP-1-first discard logic to the real-time VBR queue instead of CBR, so an admin tuning this independently from the CBR threshold can give real-time variable-bit-rate traffic, like compressed video, its own congestion tolerance separate from strict CBR circuits sharing the same card. For example, an admin sets a slightly higher cardClp0VbrRtThreshold than the CBR equivalent, reflecting that VBR-RT traffic can tolerate marginally more queue buildup before needing to shed discard-eligible cells.