This is the rn (Relative Name), the single naming segment that, appended to its parent's dn, forms the full dn for this one instance of an image-security policy controlling how strictly UCS Manager checks image signatures (e.g. Cisco-signed only vs. permissive) before letting an image be provisioned. UCS Manager derives this segment automatically from the object's own defining attribute (such as an address, index, or configured name), so seeing a distinctive rn like this is how you tell one Policy row apart from every sibling row under the same parent. For this class the rn typically looks like 'imgsec-policy-default'.