This is a bitmap (PmProfileFieldMapBasicOdu) that marks which counters within this same profile/row have been declared unsupported on this particular hardware, per the MIB's description, meaning any field flagged here should be disregarded. This bitmap exists because not every line card or ODU variant that shares the 'Basic ODU' PM profile actually implements every counter in it -- so before trusting a zero in, say, the FC or UAS field of this same row, an admin has to check this bitmap first to make sure that field isn't simply unsupported on this hardware rather than genuinely error-free; because this bin spans the whole current day and is still open, short error bursts get averaged into a slower-moving daily total -- useful for spotting a low-grade, chronic problem that the 15-minute bins would report as merely noisy. If the bit corresponding to FcOdu is set in this bitmap for a given row, an admin comparing failure counts across two different line-card models would know to exclude that field for this one rather than misread its zero as 'no failures.'