What is a ‘round’?
A round is a set number of arrows at each distance on a certain face size with a particular type of scoring. With some rounds having up to 4 distances it would get really confusing to try and convey all of this information each time you shoot so we give the combination of all this information an "easy to remember" name. These are often named after the place where they originated for UK rounds or the distance/maximum number of points for World Archery Rounds.
Outdoor rounds normally come in families. Each round in the family has the same number of arrows and the same progression of target faces. The only difference is the distances that you shoot, this allows Juniors and new archers to shoot the same competition but at shorter distances.
You can shoot whichever round you want but to claim National records and certain awards you must shoot a minimum distance.