Command recording versus parametric and variational systems, an old/new third way of parametrizing CAD models by end users

The two major ways of parametrizing in CAD are analyzed, and new results obtained with command recording are presented. The major improvement is a purely interactive definition of classic control structures in structured programming, which allows end-users to make powerful programs (parameterized pieces) with minimal programming knowledge. Despite commercial trends, neither of the methods may be considered to be universal. Depending on the precise goals of the user (prototyping, simple and well-defined components modeling, or complex components modeling) the features required for parametrization systems may vary according to the different qualities of either system