Dear Prof. Bernstein, We have developed a simple algorithm for superposing pdb files for two base pairs and creating the pdb file for the superposed pairs. In the superposed pdb file we have provided the two base pairs respectively with different temperature factors and different chain ids so that they may be viewed in different colors. Unfortunately, the rendering in Rasmol is not coming out at all well. The two gif files show the quality of rendering in different modes and the .pdb file is the file corresponding to the first superposition step. Could you please suggest a method for a better rendering using Rasmol or any other software? Thanking you in advance. Abhijit Dr. Abhijit Mitra Professor IIIT Hyderabad Hyderabad 500032 India