On type IV self-dual codes over \(\mathbb Z_4\) (Q1598788)

The authors consider Type IV (that is, all Hamming weights are even) self-dual codes over \(\mathbb Z_4\) and classify such codes of length 20, thereby extending previous results by \textit{M. Harada} and \textit{A. Munemasa} [Finite Fields Appl. 6, 244-254 (2000; Zbl 0961.94014)]. There are exactly 27 inequivalent Type IV \(\mathbb Z_4\)-codes of length 20. The highest minimum Hamming, Lee, and Euclidean weights are determined for Type IV \(\mathbb Z_4\)-codes up to length 56, with the exception of lengths 44, 48, and 52, which are still open cases.