This read-only counter tracks frames from the RAID7 array that the agent discarded because the instance field in the frame header was out of the expected range. Admins use it to identify a specific class of malformed frames distinct from checksum or framing errors, again often pointing to a version or configuration mismatch. A nonzero count here, combined with otherwise clean checksum and framing counters, tells the admin the mismatch is specifically in how instances are being addressed between array and agent.