Each tank's program is run once per turn. The data and command stacks are reset at the beginning of each turn, but memory is not, so you can carry data over in memory registers if you want. See the Forf manual for more information about the base language.
For tank specifications (sensor range, maximum speeds, etc.), see the introduction.
Forf Tanks has a data stack size of 200, and a command stack size of 500. This means your program cannot have more than 200 data items, or 500 instructions, including 2 instructions for each substack.
Forf Tanks provides 10 memory registers (0-9) which persist across invocations of your tank's program.