bitsPortCrc4 is a read-write boolean that enables or disables adding a CRC to the signal transmitted out of a BITS-OUT port. An administrator would enable this when the downstream timing-receiving equipment checks CRC4 for E1 frame integrity, and disable it for equipment that does not expect the extra CRC framing bits. For example, connecting the BITS-OUT port to E1 equipment that validates CRC4 and rejects frames without it would require this object to be enabled or the downstream device would treat every frame as errored.