8B/10B decoding includes special characters (K characters) that are often used for control functions. When CH*_RXDATA is a K character, the decoder drives CH*_RXCTRL0 High.
If RX_DEC_PCOMMA_DET is set to TRUE, the decoder drives the corresponding RXCTRL2 High whenever CH*_RXDATA is a positive 8B/10B comma. If RX_DEC_MCOMMA_DET is TRUE, the decoder drives the corresponding RXCTRL2 bit High whenever CH*_RXDATA is a negative 8B/10B comma.