A system having at least two communication systems which manage resources in each case, in which in each case an identification code is assigned to the resources for identification, and in which the resources managed by a single communication system can be differentiated on the basis of their identification codes, and having at least one application for controlling and/or monitoring the resources by transmitting messages comprising the identification code of the respective resource between the at least one application and the communication systems, characterized in that an extension of all identification codes is provided for differentiating the resources, which extension is performed at least by every communication system when sending messages and comprises an unambiguous identifier of the sending communication systems, at least whenever a plurality of resources have the same non-extended identification code in each case.