This holds the sixth of eight possible 192-bit Triple DES transmit encryption keys, entered as a 48-character hex string. Unused key slots like this one, if left at their factory-default or blank value, represent unused encryption capacity, worth checking during a security review to confirm no route is accidentally still pointing at a never-configured key. If cdmipIpRouteDesKey on some route is set to key6(6) but this object was never actually populated with a real key, that route's encryption would be relying on whatever default value the field holds, which is a configuration error worth catching.