DO...LOOP

Repeats a block of statements. Use a DO...LOOP structure when you want to repeat a set of statements an indefinite number of times, or until an EXIT control out of the loop. If you want to repeat the statements a set number of times, the FOR...NEXT statement is usually a better choice, while if you want to repeat for specific conditions, you should use the WHILE...WEND' and REPEAT...UNTIL statements.

The DO...LOOP structure gives you less flexibility than the WHILE / UNTIL statements because you cannot decide whether to end the loop when a specific condition stops being TRUE or when it first becomes TRUE. It also disallow you to test condition at either the start or the end of the loop. You can nest DO...LOOPS by putting one loop within another. You can also nest different kinds of control structures within each other.

EXAMPLE

 DO
   x = x + 1
 LOOP

Used in:
USING DO..LOOP EXITING FROM LOOP EXITING FROM NESTED LOOP MIXED DO..LOOP AND WHILE..WEND MIXED DO..LOOP AND REPEAT..UNTIL