Tetracode
= Tetracode
{title2=$T\le\mathbb F_3^4$}
= Ternary tetracode
{synonym}
The two-dimensional ternary <linear code> generated by $(0,1,1,1)$ and $(1,1,-1,0)$. Its eight nonzero words have exactly three nonzero entries, with precisely two opposite words for each position of the zero coordinate.