The attribute contains a list of 16-bit values, each of which represents an attribute type that was not understood by the server.
The attribute contains a list of 16-bit values, each of which represents an attribute type that was not understood by the server.
The UNKNOWN-ATTRIBUTES attribute is present only in an error response when the response code in the ERROR-CODE attribute is 420.
https://tools.ietf.org/html/rfc5389#section-15.9
The attribute contains a list of 16-bit values, each of which represents an attribute type that was not understood by the server.