1. A method for determining the position of structures on a mask for microlithography, wherein the position determination is effected on the basis of a comparison of an aerial image, measured by a recording device, of a portion of the mask with an aerial image determined by simulation, the method comprising measuring an aerial image of a portion of a mask for microlithography, the portion of the mask having structures; performing a plurality of simulations of aerial images of the portion of the mask based on different input parameters; and determining the position of the structures by carrying out a plurality of comparisons between the measured aerial image and the simulated aerial images, wherein the comparisons differ from one another with regard to the input parameters of the respective simulation; wherein the varied input parameters of the simulation comprise at least one of mask parameters based on the three-dimensional extent of the mask or optical parameters of an optical system for generating the measured aerial image in the recording device.