The invention relates to difluorobenzo-1,3-dioxoles, to a process for their preparation, and to their use for preparing medicaments and crop protection agents. The conveyor comprises interconnected conveyor modules, each of which includes a conveyor belt segment. The overlay is preferably transparent, and the lower-case letter is positioned in a non-interfering location relative to the upper-case letter on the alphabet keys such that both the upper-case and lower-case letters are visible to the child when installed. The method further comprises assigning uniform attributes to nodes in the hierarchy and selectively assigning at least one dimensional attribute to a node for invoking an analysis based upon the dimensional attribute.