For an explosion-proof connection of two electric line ends, the contact elements are accommodated in two tubes, which can be joined in an explosion-proof manner. The chassis has two module mountings which are laterally spaced form each other with respect to the direction of travel of the machine, and each mounting being adapted to receive a respective outer end of the module. A cleaning apparatus that cleans the intermediate transfer belt of the intermediate transfer apparatus is supported by an upper rail and a lower rail so as to be attachable to and detachable from the intermediate transfer apparatus. In one embodiment, gain andor linearity performance of the variable gain transconductor are selectively controllable by selecting or deselecting a number of operating transconductance cells. Notably, in a preferred aspect of the invention, logic can be included for identifying an asynchronous correlator for each one of the individual Web service instance invocations and for storing the asynchronous correlator in association with corresponding ones of the stored checkpoint data. Null-padding is not visible outside the edge nodes and only the information content is subject to transfer rate regulation to ensure high efficiency and high service quality.