Comparison of the human and mouse sequences in the C-delta to C-alpha region (Wilson et al. 92, Koop et al. 92, Koop et al. 94), using RepeatMasker output giving positions of human repeats and mouse repeats, plus exon locations in the human sequence, yields PIP output in which regions of high sequence conservation do not correspond to coding regions. Note that in all of our other examples, sequence conservation tends to drop off very sharply at coding-region boundaries.