Cut-offs for over- and under-expressed genes can be selected. The user can also choose the number of arrays on which the expression needs to fulfill the selected cut-offs. By default, the arrays are not scaled to their mean values, which is most appropriate for 1-color arrays, and the genes that fall inside the specified expression range are selected, which makes sense when trying to filter low quality or saturated probes. It is also possible to select the genes that fall outside the selected range, which, when combined with the mean scaling option, is a convenient way to filter out invariant genes in 2-color experiments.