The extended Nadler code is unique (Corresp.)

Constructions for a 32-word binary code of length 12 and minimum distance 5 were given by Nadler in 1962 and van Lint in 1972. These codes are not equivalent as their distance distributions are not the same. That their extended codes of length 13 are equivalent is proved. It is shown that up to a permutation of the coordinates, there is an essentially unique way to construct the extended code. This unique extended code contains only two inequivalent punctured codes of length 12.