Abstract: A device for determining the nature of relationships between on the one hand data peculiar to one unit or a group of separate units, and on the other hand data of another unit or another group of separate units pertaining to the same assembly, includes a transparent support corresponding to each unit or group of units, each support being arranged by means of a matrix of addresses, wherein on the support corresponding to each unit or groups of separate units are inscribed, at any address, corresponding to the data peculiar to the other units or group of separate units, one or more symbols distinctive of each nature of relationship between the data peculiar to the unit or groups of separate units corresponding to each support and the data peculiar to the other units or groups of units of the assembly. This permits the symbols to be simultaneously read when superimposing the cards corresponding to the relationship to be studied.