| roon | symmetric | purpose |
|---|---|---|
path  | yes | move  straight ahead |
shimmy  | no | move 1/2 cell left/right |
turn  | no | turn around |
long turn  | no | turn around |
switch  | no | divert based on a checker or  |
canute  | no | divert based on a checker or |
xor  | yes | implement XOR gate |
trap  | no | hold in place until released |
crossing  | yes | swap two streams |
distributor  | yes | spread out |