Rasmol routinely displays i..i+2 "Hbonds" in beta strands that are clearly bogus. These bogus Hbonds are not reported by DSSP. The Kabsch and Sander formulation includes some geometric considerations that rasmol seems to have simplified away to its detriment. ------------------------------------------------------------ Kevin Karplus karplus at soe.ucsc.edu http://www.soe.ucsc.edu/~karplus Professor of Biomolecular Engineering, University of California, Santa Cruz Undergraduate and Graduate Director, Bioinformatics (Senior member, IEEE) (Board of Directors, ISCB) life member (LAB, Adventure Cycling, American Youth Hostels) Effective Cycling Instructor #218-ck (lapsed) Affiliations for identification only.