Understanding the links between parameters — which one depends on which one and how — is crucial for the process of constructing a box. While a box is being created out of discrete components or a ready design is being edited — deleting objects or components, or attaching or drawing new ones — often situations arise when some parameters depend on and define other parameters. For example, when a tongue must be inserted into an opening, the sizes of the tongue and the opening must fit perfectly. Parameters are used for the sizes of the components — length and height — to ensure that they form constructional unity when assembled. Since the tongue and the opening are two discrete components, by necessity the parameters that control the length and height depend on one another.
The need for constructional consistency requires designers to be able to follow in their calculations which parameter depends on which one. This section tells about the three levels of dependency between parameters, and how to explore dimensions and trace the strings of parameters behind them.