Every slave is equipped with slots (mounting positions). Each slot can be occupied by a module. An empty slot can be specially identified (empty module).
A DP slave with a fixed configuration is equipped with one or more permanently adjusted modules. A modular DP slave can have one or more modules, which can be selected from a list of possible modules. It is only in the extended functionalities that differences are allowed to arise between planned modules and connected modules.
Each module is described by one or more identifiers. Two formats exist: