The status responses are "OK", "NO", "BAD", "PREAUTH", "BYE". In these responses, any additional data beyond the status code or the optional response code is treated as HumanReadable text. For other responses ("FLAGS"), the rest of the response will contain information specific to this response (for instance, a set of flags for "FLAGS" response). This information is in IMAP4 format and is not directly intended to be read by humans, and will be available in property value.
Thus, both HumanReadable properties cannot be non-null for the same response. If one of these properties is non-null, another will be null. Both properties can be null, however.and