Defining the structure of irregular nucleic acids: conventions and principles.

The algorithm "Curves", that we have recently presented in this journal (J. Biolmol. Str. Dynam. 6, 63-91 (1988], is updated to take into account the conventions developed at the Cambridge meeting on DNA curvature (September 1988) and extended to the calculation of local parameters. In addition, the principles which govern the choices made in establishing the Curves algorithm are compared with the approaches adopted by other authors.