Hi Andy, I have now updated and made some important corrections for the equations for your model in the relax manual. I have also added a description as to why these equations do not match those of your publication. For example E0 is redefined as tau_cp.E0 here. If you could have a look and provide some feedback, it would be appreciated. Some of the redefinitions of the symbols, as used in the code, may not be as you intended, so please advise. I have uploaded a temporary copy of the relax manual to http://download.gna.org/relax/manual/relax_temp.pdf. You will find your model on page 155 (or 181 of the PDF). Note that the model is also listed in the dispersion model table on page 144 and the software comparison table on page 187. As mentioned before, you are welcome to have this modified as you wish. You are even welcome to make the changes yourself, if you so wish. This section of the manual will be an important way that relax users are introduced to the details of your model. Cheers, Edward P. S. If you have an svn copy of relax, just run 'svn up' to obtain these changes.