There are two main exemptions that an underwriter may claim as defense against a civil suit alleging an untrue statement in a registration. One exemption is 'reasonable investigation and grounds for belief.' The other is ______ ___ ____________. A party to a civil suit may claim an exemption based on no knowledge of the false statement or omission, if the party immediately advised the SEC of this fact (upon becoming aware of it) and also gave reasonable public notice.