The MIB's DESCRIPTION for cucsLsFcZoneRn is only the auto-generated stub 'Cisco UCS ls:FcZone:rn managed object property', but the 'rn' property name together with its SnmpAdminString type tell us this column, on an FC SAN zone defined as part of a service profile's storage configuration, 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 service-profile FC zone, which is what changes from row to row while the parent path stays fixed, so it is useful for telling sibling service-profile FC zone 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 'fc-zone-Zone_DB01'.