  Triorthogonal codes are a class of quantum error correcting codes used in
magic state distillation protocols. We classify all triorthogonal codes with
$n+k \le 38$, where $n$ is the number of physical qubits and $k$ is the number
of logical qubits of the code. We find $38$ distinguished triorthogonal
subspaces and show that every triorthogonal code with $n+k\le 38$ descends from
one of these subspaces through elementary operations such as puncturing and
deleting qubits. Specifically, we associate each triorthogonal code with a
Reed-Muller polynomial of weight $n+k$, and classify the Reed-Muller
polynomials of low weight using the results of Kasami, Tokura, and Azumi and an
extensive computerized search. In an appendix independent of the main text, we
improve a magic state distillation protocol by reducing the time variance due
to stochastic Clifford corrections.
