This counts errored blocks -- E1 frames in which at least one bit was corrupted -- detected on this E1 port. EB is the broadest block-error counter in this table, since SES and most BBE events are drawn from it, so a rising EB count on this port, even before SES climbs, is the earliest sign of block-level corruption worth checking -- and this specific object covers the current, still-open 15-minute interval -- a value that keeps climbing until the interval closes and rolls into history. For example, so far in the current, still-running 15-minute interval, this E1 port might show this counter at 5 -- a concrete count the admin can trend against neighboring bins to judge whether the condition it reflects is worsening.