The swimmers rules

The medley relay has a different stroke order. In the medley, the order is: 1) backstroke, 2) breaststroke, 3) butterfly, and 4) freestyle. Each of the four swimmers in the relay swims a predetermined distance, dependent on the overall length of the relay. The three relay lengths are 200 meters or yards, 400 meters or yards, and 800 meters or yards (which is only swum freestyle). In a 50 meter pool, each swimmer swims one length for the 200 relay, two lengths for the 400 relay, and four lengths for the 800 relay. In a 25 meter or yard pool, each swimmer swims two lengths for the 200 relay, four lengths for the 400 relay, and eight lengths for the 800 relay. There have also been 100 yard relays that have been done by eight and under swimmers, but is very rare except in summer recreation leagues. Many full-size competition pools in the United States have a length of 50 meters and a width of 25 yards (the Olympic pool size, allowing both short course (25 m or 25 yd pool) and long course (50 m pool) races to be held.

There are several types of officials[5]:

* A starter sends the swimmers off the blocks and may call a false start if a swimmer leaves the block before the starter sends them;
* finish judges determine the order of finish and make sure the swimmers finish in accordance with the rules (two hands simultaneously for breaststroke and butterfly, on the back for backstroke, etc.)
* turn judges check that the swimmers' turns are within rules;
* stroke judges check the swimmers' strokes;
* timekeepers time the swims;
* the referee takes overall responsibility for running the race and makes the final decisions

If an official catches a swimmer breaking a rule concerning the stroke he or she is swimming, that swimmer is said to be disqualified (commonly referred to as a "DQ") and the swim is not considered valid.