A [[linear code|binary code]] is called an '''even code''' if the [[Hamming weight]] of all its codewords is even. An Eveneven code should have a generator polynomial that include (1+''x'') minimal polynomial as a product. Furthermore, a binary code is called [['''doubly-even]]''' if the Hamming weight of all its codewords is divisible by 4. An even code which is not doubly-even is said to be strictly even.
Examples of doubly-even codes are the extended binary [[Hamming code]] of [[block length]] 8 and the [[extended binary [[Golay code]] of block length 24. These two codes are, in addition, [[self-dual code|self-dual]].
