Description: This indicates the defect signalling in addition to the report towards the control unit (CU). It is coded as a bit map. The various bit positions are:

1 : ERI or RSA (error indicator, bit inserted in theactive maintenance cells to warn neighbour boards that an error is detected), 2 : P-FERF or RDI-P or RAI (path section far end received failure indication sent to the origin of the defect), 4 : MS-FERF or RDI-L (multiplexing section far end received failure indication sent to the origin of the defect), 8 : ATM-AIS (ATM alarm indication signal is sent on a line defect towards the network handler dealing with VP/VC AIS management), 32 : RLED (the status led must be set permanent red), 64 : NB-AIS (not ATM alarm indication signal is sent on a line defect towards the AEI side), 128 : TCK (trunk conditioning: in circuit emulation, a specified pattern is sent in timeslots, except TS0: a pattern for TS16, another one for other TS).