
>>-DO--| repetitor |--| conditional |--;--+-----------------+--->
| .-------------. |
| V | |
'---instruction-+-'
>--END--+------+--;--| repetitor |------------------------------>
'-name-'
>--+-name=expri--+-----------+--+-----------+--+------------+-+-><
| '-TO--exprt-' '-BY--exprb-' '-FOR--exprf-' |
+-FOREVER--------------------------------------------------+
'-exprr----------------------------------------------------'
conditional
|--+-WHILE--exprw-+---------------------------------------------|
'-UNTIL--expru-'
DO groups instructions together and optionally processes them
repetitively. During repetitive execution, a control variable (
name)
can be stepped through some range of values.