There are two successive postgraduate "degrees": kandidat nauk ("Candidate of science") and doktor nauk ("Doctor of science"). Both are a certificate of scientific, rather than academic, achievement, and must be backed up by original/novel scientific work, evidenced by publications in peer-reviewed journals and a dissertation defended in front of senior academic board. The titles are issued by Higher Attestation Commission of the Ministry of Education. A degree is always awarded in one of 23 predetermined fields of science, even if the underlying achievement belongs to different fields. Thus it is possible to defend two degrees of "kandidat" independently, but not simultaneously; a "doktor" in one field may also be a "kandidat" in a different field.