188.8.131.52 If an otherwise valid HTTP PUT request is received that contains properties the server chooses not to persist, e.g. unknown content, LDP servers must respond with an appropriate 4xx range status code [RFC7231]. LDP servers should provide a corresponding response body containing information about which properties could not be persisted. The format of the 4xx response body is not constrained by LDP. LDP servers expose these application-specific constraints as described in section 4.2.1 General.