Usage:
/FOR variable start
end commands
The variable will take on all numeric values between start and end, inclusive. The commands will be executed once for each of the values. If end is less then start, commands will not be executed.
Example:
"/for i 0 9 say $[10 - i]
"
would cause you to execute the commands "say 10", "say 9", ... "say 1".
See: /while