This is the ending tone index for the receive frequency band paired with cvdslMCMConfProfileRxBandStart, together defining exactly which subcarriers this line listens on for downstream (or upstream, depending on which end) data. As with the transmit band, getting this stop index wrong relative to the start could define an invalid receive range, which the profile's activation validation should catch before the profile reaches a live line. This pairing is what a provider would adjust to intentionally exclude specific problematic frequencies from the receive path, separate from any transmit-side exclusions.