Security Level Capability (SL-C) describes the level of security requirements an industrial automation component is designed and assessed as capable of supporting under IEC 62443. It is a component-level measure, not a statement that a facility or deployed system has achieved that security level.
In practice, an SL-C rating can help buyers compare component capabilities and guide security assessments. A protocol or component certified at a given level does not automatically make every product implementing it secure: implementation, configuration, key management, network architecture, updates, and monitoring all matter. Defenders should verify what exact component and standard scope were assessed, then evaluate the deployed system’s controls and operation separately.