to select the powder diffractometer and its corresponding resolution used to record the 'tbig.dat' data file. Click on the 'OK' button starts a first run of the profile fitting procedure with only intensities as refined parameters. A 'tbig.xrf' file (columns file with Yobs, Ycalc, Yobs-Ycalc, background, Bragg_position, intensity, FWHM, Eta) is then automatically created and displayed in the WinPLOTR windows :