This field reports the number of in error packets received on the port, exposed here as cienaCesPmExtendedTxRxHist24HBinRxInErrorPkts. On this Ciena CES port's PM data, these are frames the MAC accepted for delivery but flagged with a receive-side error (bad FCS, alignment, or a similar framing fault), so any nonzero movement here on an otherwise up link points at a cabling, optics, or upstream-device problem specific to this port; and this lives in one of the rotating 24-hour daily history bins for the port's extended Tx/Rx PM group, so it captures a full day's worth of activity that you can compare day-over-day against the other retained daily bins. For example, a healthy port would sit at 0 for in-error frames in this bin; even 12 is enough to warrant a look, since this class of counter isn't supposed to move under normal operation.