An array of up to 512 real Quiet Line Noise values in dBm/Hz for the respective transmission direction. It is designed for up to 512 (downstream) sub-carriers. The number of utilized values on downstream direction depends on NSCds, and on upstream direction it depends on NSCus. This value is referred to here as NSC. Each array entry represents the QLN(f = i*Df) value for a particular sub-carrier index i, (0 <= i < NSC). The QLN(f) is represented as ( -23-n(i)/2), with n(i) in the range 0 to 254. A special value n(i)=255 indicates that no measurement could be done for the subcarrier because it is out of the passband or that the noise PSD is out of range to be represented. This parameter is applicable in loop diagnostic procedure and initialization. Each value in this array is 8 bits wide.