When a valid formula has been entered in the Formula text box in the Formula Editor, the Formula diagram displays the formula in a hierarchical view using a tree control. When collapsed, each node of the tree shows either an operator, a function, the name of a data set, a global variable, or a constant along with the arguments on which the operator or function acts. In the case of a function, this is followed by two colons and the function prototype which helps the user determine the purpose of each argument. Nodes for operators or functions can be expanded. When expanded, each daughter node displays one of the arguments for the operator or function.
