There is provided a system for facilitating a conference call. The leaves are slightly smaller than in the genus. The operation object desktop is not directly operated, and therefore the loss and disorder of the content of the operation object desktop can be avoided. For the purpose of generating the gas curtain, at least one slit nozzle and an efficient gas sink are arranged laterally opposite one another with respect to an optical axis of the beam bundle in order to limit the gas curtain in a spatially defined manner and to remove it again from the vacuum chambers as completely as possible. An Integration Controller communicates with an Event Scheduling System via a Scheduling System Interface. , the source filer can create a log file when the source filer flushes its cache.