Abstract: A method for operating a data processing unit according to a program for creating individual shelf images for a multitude of points of sale (POS) of a trading firm, including accessing assortment data which define an individual assortment of different items with attributes for every POS, offering a user to interactively define blocks via input- and output devices, each block comprising items with at least one attribute specific for the block, accessing the blocks in a data memory, accessing shelf data with data of at least one shelf of every POS in a data memory, offering the user to interactively develop a sequential order of placement rules, accessing the order of placement rules in a data memory and for each POS, applying placement rules, and determining the placement positions of items in the shelf of the POS, and visualizing the placement positions of the items in a shelf image.