3.3.5.1.8 MS-User-IPv6-Address
If the userIpv6Address parameter of the SendRadiusAccessRequest abstract interface (section 3.3.4.1) is set to a NULL address (all bytes are set to zero), this attribute MUST NOT be set. Otherwise, the attribute-specific value is obtained by serializing the userIpv6Address parameter to the format described in section 3.2.5.1.14.