The type and the power of a given rack are related to each other. In fact, the maximal power provided by a rack depends on its type, so its type must be chosen according to the power this rack must provide. Solver allows you to easily express this dependence by writing the expression rackPower(_type).

This interdependence is implemented through the use of an element constraint. The dependence between type and price, and type and number of slots is also implemented with such a constraint.