This read-only Unsigned32 value (2-10, default 7) is the number of consecutive one-second intervals of excessive block errors required before this OTU4 (about 111.8 Gbit/s) line facility is declared signal-degraded (SDBER). Tuning this controls how persistent elevated error rates must be before a degrade alarm fires, avoiding a nuisance alarm from one noisy second on a high-rate line. For example, with the default of 7 on the OTU4 facility on slot 3, seven straight seconds of block errors above threshold are needed before an SDBER alarm is raised, not just one bad second.