Feature extraction. Segments of an electropherogram: The segment preceeding the lower marker is designated the pre-region. The marker-region coincides with the area occupied by the lower-marker peak. The 5S-region covers the small rRNA fragments (5S and 5.8S rRNA, and tRNA). The 18S-region and 28S-region cover the 18S peak and 28S peak, respectively. The fast-region lies between the 5S-region and the 18S-region. The inter-region lies between the 18S-region and the 28S-region. The precursor-region covers the pre-cursor RNA following the 28S-region. And finally the post-region lies beyond the precursor-region.