The MSB (31st bit) must be zero.Bit j[30:0] is the byte mask. If Bit 1/2/3/4 (byte number) of the byte mask is set the CRC block processes the Filter 1/2/3/4 Offset + j of the incoming packet(PWKPTR is 0/1/2/3).RWKPTR is 0:Filter 0 Byte Mask .RWKPTR is 1:Filter 1 Byte Mask RWKPTR is 2:Filter 2 Byte Mask RWKPTR is 3:Filter 3 Byte Mask RWKPTR is 4:Bit 3/11/19/27 specifies the address type defining the destination address type of the pattern.When the bit is set the pattern applies to only multicast packets