This read-only enumerated value reports whether a PRBS (pseudo-random bit sequence) test running at the facility level (such as an ODU or OTU test point) is notApplicable, inSync, outSync, or errSync, defaulting to notApplicable. Operators watching this during a circuit-turnup test want to see 'inSync' to confirm the receiving end is correctly locked onto the known test pattern before trusting any bit-error count. For example, testSignalFacilityStatusPrbsSync showing 'outSync' during a new wavelength's acceptance test would tell the technician the far end hasn't locked onto the PRBS pattern yet, so any error count collected so far should be disregarded.