RADIUS attribute from rfc2865
This Attribute indicates text which MAY be displayed to the user. When used in an Access-Accept, it is the success message. When used in an Access-Reject, it is the failure message. It MAY indicate a dialog message to prompt the user before another Access-Request attempt. When used in an Access-Challenge, it MAY indicate a dialog message to prompt the user for a response. Multiple Reply-Message's MAY be included and if any are displayed, they MUST be displayed in the same order as they appear in the packet. A summary of the Reply-Message Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | Text ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 18 for Reply-Message. Length >= 3 Text The Text field is one or more octets, and its contents are implementation dependent. It is intended to be human readable, and MUST NOT affect operation of the protocol. It is recommended that the message contain UTF-8 encoded 10646 characters.