This operator takes three arguments; if the first expression or condition evaluates to true (1), the second argument's value is returned, otherwise the third argument's value is returned. The second and/or third arguments need not have return values, but can be statements with one or more actions to perform. If no return value exists, invalid is returned.
ZBar(10, 200, 60, 10, level > 100 ? 12 { red } : 10 { green });
In this example, color of the bar drawn on the screen will be based on a variable called level. When level is greater than 100, the bar will be red, when it is equal to or less than 100, the bar will be green. The same thing could have been accomplished by using the Cond or IfElse functions.