This Counter32 object counts the number of times a valid-length packet arrived at a port with at least one invalid data symbol detected, incrementing only once per carrier event regardless of collisions during that event. An admin troubleshooting physical-layer signal integrity issues on a link watches this counter for growth as a sign of line-level encoding problems rather than higher-layer frame errors. For example, a port with rising symbol errors alongside otherwise clean traffic would point the admin toward a marginal transceiver or fiber connection rather than a cabling or configuration issue.