This is a bitmask selecting which predefined spectral notches - vendor-specific notches or specific amateur radio band exclusions like the 30m, 40m, or 80m bands - this single-carrier line's transmit power spectrum should avoid, functioning as a convenient shorthand compared to manually defining individual PSD table entries. It's how a provider ensures regulatory compliance for spectrum sharing with licensed amateur radio operators without needing to hand-calculate exact tone ranges for each band. A line deployed in a region with active amateur radio use nearby would have the relevant amateurBand bits set here specifically to notch out those frequencies and avoid causing, or receiving, interference.