This read-only on/off attribute, defaulting to off, indicates whether a Section-layer Loss of Frame condition is present at the OC-3 port. It gives an administrator a SONET framing-level diagnostic distinct from a raw loss of signal, useful when the fiber has light but the receiving equipment cannot lock onto valid frames. For example, an operator seeing this attribute turn on while hcxOc3PortSectionLOS remains off would suspect a framing mismatch or clock issue rather than a physical fiber break.