The WANTED method is a non-contact optical technique to obtain simultaneously both the dispersive refraction index, n(lambda), and thickness, d, of weakly-absorbing films with d greater than or equal to 0.71n lambda. It uses both spectral and angular reflectance scans, so it is necessarily a spectrogonio(photo)metric instrument. This method is practically insensitive to thickness non-uniformity, wavelength and angular bandwidth, moderate surface roughness(sigma < lambda/10), index inhomogeneity and even a systematic angle error. Here a more general formulation of the method is presented along with considerations related to accuracy not given earlier. New experimental results are presented to illustrate the accuracy, reliability and advantages of using WANTED : a non-uniform gelatin film on glass(similar to 5 mu m) and a biaxial polyester (polyethylene terephthalate) foil(similar to 50 mu m) with a slightly rough surface.