On Type II codes over F/sub 4/
Koichi Betsumiya, Thomas Aaron Gulliver, Masaaki Harada, Akihiro Munemasa · IEEE Transactions on Information Theory · 2001
Previously, Type II codes over F/sub 4/ have been introduced as Euclidean self-dual codes with the property that all Lee weights are divisible by four. In this paper, a number of properties of Type II codes are presented. We construct several extremal Type II codes and a number of extremal Type I codes. It is also shown that there are seven Type II codes of length 12, up to permutation equivalence.