While all modern Western square dancing uses a common set of call definitions, which specify the basic dance movements and outcome of each call, there are many possible "frills" or "flourishes" -- extra movements that can be added without changing the resulting position.
A few of these are traditional among adult dancers in certain geographic regions, but youth dancing generally includes more of them regardless of location.
Each square consists of four "boys" (or "gentlemen") and four "girls" (or "ladies"), who maintain this identity throughout a dance tip.
In addition, a relatively small number of calls, but ones that are commonly used, involve a different dance action for the boys and girls.
However, for this to work it is not necessary that the biological sex of the dancers match the roles that they are playing at any given time, e.g., it is possible for a woman to dance the "boy's part".
Many clubs are dominated by married couples, most of the dancers are not familiar with dancing the other part, and there may even be social stigma associated with such role reversals.
Sometimes it is accepted, but is seen only as a way to deal with special circumstances, such as to accommodate everybody when there are "extra" women.
Although such clubs are becoming increasingly rare as the square dance population ages and couples are split by death or divorce, they may still be found.