The typical system identification procedure requires powerful and versatile software means. In this paper we describe and exemplify the use of a prototype identi#cation software tool, applicable for the rather broad class of multi input single output model structures with regressors that are formed by delayed in- and outputs. Interesting special instances of this model structure category include, e.g., linear ARX and many semi-physical structures, feed-forward neural networks, radial basis function networks, hinging hyperplanes, certain fuzzy structures, etc., as well as anyhybrid obtained by combining an arbitrary number of such approaches