Extremal Type II [formula omitted]-codes constructed from binary doubly even self-dual codes of length [formula omitted].

In this note, we demonstrate that every binary doubly even self-dual code of length 40 can be realized as the residue code of some extremal Type II Z 4 -code. As a consequence, it is shown that there are at least 94356 inequivalent extremal Type II Z 4 -codes of length 40 . [ABSTRACT FROM AUTHOR]