Hi, I would like to know if the Rex values given in the xml result file of relax 1.3 are expressed in s-1 or if it is the result of the following formula: Rex/(2 * π * freq)**2? The values I get (~3E-19) seem to come from the scaling equation, but in the result file, these values are associated with a field strength: <rex desc="Chemical exchange relaxation (800 MHz)" ieee_754_byte_array="[197, 23, 28, 207, 173, 151, 0, 60]"> 1.124351254e-19 Maybe the field strength associated with the values in the result file are remnants of relax 1,.2, where Rex were given in s-1... Thank you very much for your help, Pierre-Yves -- ==================================== Pierre-Yves Savard, Ph.D. Professionnel de recherche biochimie Pav. Marchand, local 3252 1030 avenue de la médecine Université Laval, Québec, Qc, G1V 0A6 Tél: 418.656.2131 #4530 ====================================