A first data structure stores one or more components of a modular system, wherein each component includes a quantity of features. A second data structure stores one or more component position numbers, wherein at least one component is assignable to each of the one or more component position numbers, and each design variant is describable by assignment of the components of the modular system to component position numbers of the second data structure. A third data structure stores one or more rules, wherein each rule is to set at least two component position numbers in a relationship, and an assembly module in a computing device is to select the rules from the third data structure that correspond to the one or more component position numbers, and to cause a design drawing to be displayed according to the selected rules.