This attribute represents the number of active data subcarriers within the OFDM downstream channel (i.e. this exclude subcarriers for continuous pilots and the PLC). For 4K FFT mode, the maximum number of subcarriers including continuous pilots and the PLC cannot exceed 3800, and for 8K FFT mode, the maximum number of active subcarriers including continuous pilots and the PLC cannot be greater than 7600. However, there are a minimum of 56 continuous pilots in a 192MHz channel that has no exclusions, and the size of the PLC is 8 subcarriers for 4K FFT mode and 16 subcarriers for 8K FFT mode. Therefore the maximum value of NumActiveSubcarriers is 3736 (or 3800 - 56 - 8) for 4K FFT mode and 7528 (or 7600 - 56 - 16) for 8K FFT mode.