Electric and electronic appliances, apparatus and instruments, including electric, electronic, opto-electronic, analogue, digital, wire-based and wireless communication systems and apparatus, including private branch exchanges; telephones and telephone systems, including system telephones; apparatus for acquisition, computing, broadcasting, transmitting, exchanging, storing, receiving and outputting of speech, text and data, including routers and switching devices; telecommunication devices; devices for the aforementioned appliances and apparatus, including modems, converters, data output printers and plotters, printed circuit boards and hard-disc, tape, floppy disc and cassette drive assemblies; computer programs recorded on data carriers