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474 SIGNALING CONNECTION CONTROL PARTPar.5 Refusal Cause. This one-octet parameter appears in the ConnectionRefused (CREF) message only. It indicates the reason why a requested connectioncannot be set up, for example:BitsRefusal Cause 8 7 6 5 4 3 2 1(a) Refused by called subsystem 0 0 0 0 0 0 1 1(b) Unknown destination address 0 0 0 0 0 1 0 0(b) Destination inaccessible 0 0 0 0 0 1 0 1(b) Subsystem failure 0 0 0 0 1 0 1 0Cause (a) indicates that the called subsystem has refused the connection. Causes(b) indicate that a SCCP along the message path was unable to transfer the connectionrequest message.Par.6 Release Cause. This is a one-octet parameter that appears in Released(RLSD) messages only. It indicates why a signaling connection is being released,for example:BitsRelease Cause 8 7 6 5 4 3 2 1(a) Originated by subsystem 0 0 0 0 0 0 1 1(b) Subsystem failure 0 0 0 0 1 0 0 0(b) Network failure 0 0 0 0 1 0 1 0Cause (a) indicates a normal release of a connection, by one of the subsystems.Causes (b) originate at a SCCP and indicate that the connection has been releasedbecause of a failure.Par.7 Return Cause. This is a one-octet parameter that appears in UnitdataService (UDTS) messages only. It indicates why a unitdata message is beingreturned, for example:BitsReturn Cause 8 7 6 5 4 3 2 1(a) No translation for an address of this 0 0 0 0 0 0 0 0nature(b) No translation for this specific address 0 0 0 0 0 0 0 1(c) Failure of called subsystem 0 0 0 0 0 0 1 1(d) Subsystem not equipped 0 0 0 0 0 1 0 0(e) Signaling network failure 0 0 0 0 0 1 0 1(f) Other failures 0 0 0 0 0 1 1 1