A resonant amplitude grating mark has a periodic structure configured to scatter radiation incident on the mark. The scattering is mainly by coupling of the incident radiation to a waveguiding mode in the periodic structure. The effective refractive indexes and lengths of portions of the periodic structure are configured to provide an optical path length of the unit cell in the direction of periodicity that essentially equals an integer multiple of a wavelength present in the radiation. The effective refractive indexes and lengths of the portions are also configured to provide an optical path length of the second portion in the direction of periodicity that is selected from 0.30 to 0.49 of the wavelength present in the spectrum of the radiation.