3.1 is a certificate issued by the mill which declares that the plates
are in compliance with the specification and includes the test results. Test results are validated by the mill's in–house test department which has to be independent of the manufacturing department.
3.2 Certification is more rigorous and the certificate is prepared
jointly by the mill's inspection department and an independent 3rd
party inspectors are TUV or Lloyds Register. The certificate states
that the plates are compliant with the relevant specification and the
mill test certificate is included