DM2003 provides several curve fitting tools available in Process|Fitting submenu. In comparison with NLSF, linear fitting has more limited applications. However, it is much more fast and straightforward and does not require initial parameter evaluations. This feature makes it more convenient for various automatic fitting routines (see IDMApplication2 interface for more details). Unfortunately linear fitting method has serious restriction: you can fit only several predefined model functions (or function classes).
First you should plot data to be fitted since this tool works only with active plot serie; then select appropriate menu item to load Linear Fitter HTML application into the Browser window. Your data will be plotted in a new temporary data window.