The MIB's DESCRIPTION for cucsLicenseSourceRn is only the auto-generated stub 'Cisco UCS license:Source:rn managed object property', but the 'rn' property name together with its SnmpAdminString type tell us this column, on the license source configuration UCS Manager consults for a fabric interconnect's license server, holds this object's relative name as UCS Manager's data model defines it, exposed here as a read-only SNMP value (read-only). The Rn is just the last arc of that same Dn — the naming-coordinate segment specific to this one license source, which is what changes from row to row while the parent path stays fixed, so it is useful for telling sibling license source entries apart under the same parent without printing the whole Dn. Continuing the earlier example, the Rn here would just be the trailing segment, something like 'license-fabric-A'.