effect

An effect is a category of behavior that a function can exhibit.

In the example below, the code says that a function is named IsCriticalHealth and takes an integer value as input through the Health parameter. Next, it says that the effects the function exhibits are decides and transacts, which means the function is a failure context and its actions can be rolled back if the function fails. If the Health value that is passed as input to the function is greater than 0.0 and less than or equal to 30.0, then the function succeeds. Otherwise the function fails, and the context that called the function must handle the failure.

IsCriticalHealth(Health : float)<decides><transacts> : void =
    ((Health > 0.0) && (Health <= 30.0))

For more on this, see Specifiers and Attributes.